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Diffstat (limited to 'sys/kern/vfs_bio.c')
| -rw-r--r-- | sys/kern/vfs_bio.c | 4062 |
1 files changed, 4062 insertions, 0 deletions
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c new file mode 100644 index 0000000..32a1089 --- /dev/null +++ b/sys/kern/vfs_bio.c @@ -0,0 +1,4062 @@ +/*- + * Copyright (c) 2004 Poul-Henning Kamp + * Copyright (c) 1994,1997 John S. Dyson + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * this file contains a new buffer I/O scheme implementing a coherent + * VM object and buffer cache scheme. Pains have been taken to make + * sure that the performance degradation associated with schemes such + * as this is not realized. + * + * Author: John S. Dyson + * Significant help during the development and debugging phases + * had been provided by David Greenman, also of the FreeBSD core team. + * + * see man buf(9) for more info. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/bio.h> +#include <sys/conf.h> +#include <sys/buf.h> +#include <sys/devicestat.h> +#include <sys/eventhandler.h> +#include <sys/fail.h> +#include <sys/limits.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/mount.h> +#include <sys/mutex.h> +#include <sys/kernel.h> +#include <sys/kthread.h> +#include <sys/proc.h> +#include <sys/resourcevar.h> +#include <sys/sysctl.h> +#include <sys/vmmeter.h> +#include <sys/vnode.h> +#include <geom/geom.h> +#include <vm/vm.h> +#include <vm/vm_param.h> +#include <vm/vm_kern.h> +#include <vm/vm_pageout.h> +#include <vm/vm_page.h> +#include <vm/vm_object.h> +#include <vm/vm_extern.h> +#include <vm/vm_map.h> +#include "opt_compat.h" +#include "opt_directio.h" +#include "opt_swap.h" + +static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); + +struct bio_ops bioops; /* I/O operation notification */ + +struct buf_ops buf_ops_bio = { + .bop_name = "buf_ops_bio", + .bop_write = bufwrite, + .bop_strategy = bufstrategy, + .bop_sync = bufsync, + .bop_bdflush = bufbdflush, +}; + +/* + * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has + * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. + */ +struct buf *buf; /* buffer header pool */ + +static struct proc *bufdaemonproc; + +static int inmem(struct vnode *vp, daddr_t blkno); +static void vm_hold_free_pages(struct buf *bp, int newbsize); +static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, + vm_offset_t to); +static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); +static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, + vm_page_t m); +static void vfs_drain_busy_pages(struct buf *bp); +static void vfs_clean_pages_dirty_buf(struct buf *bp); +static void vfs_setdirty_locked_object(struct buf *bp); +static void vfs_vmio_release(struct buf *bp); +static int vfs_bio_clcheck(struct vnode *vp, int size, + daddr_t lblkno, daddr_t blkno); +static int buf_do_flush(struct vnode *vp); +static int flushbufqueues(struct vnode *, int, int); +static void buf_daemon(void); +static void bremfreel(struct buf *bp); +#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ + defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) +static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); +#endif + +int vmiodirenable = TRUE; +SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, + "Use the VM system for directory writes"); +long runningbufspace; +SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, + "Amount of presently outstanding async buffer io"); +static long bufspace; +#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ + defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) +SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, + &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); +#else +SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, + "Virtual memory used for buffers"); +#endif +static long maxbufspace; +SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, + "Maximum allowed value of bufspace (including buf_daemon)"); +static long bufmallocspace; +SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, + "Amount of malloced memory for buffers"); +static long maxbufmallocspace; +SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, + "Maximum amount of malloced memory for buffers"); +static long lobufspace; +SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, + "Minimum amount of buffers we want to have"); +long hibufspace; +SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, + "Maximum allowed value of bufspace (excluding buf_daemon)"); +static int bufreusecnt; +SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, + "Number of times we have reused a buffer"); +static int buffreekvacnt; +SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, + "Number of times we have freed the KVA space from some buffer"); +static int bufdefragcnt; +SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, + "Number of times we have had to repeat buffer allocation to defragment"); +static long lorunningspace; +SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, + "Minimum preferred space used for in-progress I/O"); +static long hirunningspace; +SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, + "Maximum amount of space to use for in-progress I/O"); +int dirtybufferflushes; +SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, + 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); +int bdwriteskip; +SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, + 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); +int altbufferflushes; +SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, + 0, "Number of fsync flushes to limit dirty buffers"); +static int recursiveflushes; +SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, + 0, "Number of flushes skipped due to being recursive"); +static int numdirtybuffers; +SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, + "Number of buffers that are dirty (has unwritten changes) at the moment"); +static int lodirtybuffers; +SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, + "How many buffers we want to have free before bufdaemon can sleep"); +static int hidirtybuffers; +SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, + "When the number of dirty buffers is considered severe"); +int dirtybufthresh; +SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, + 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); +static int numfreebuffers; +SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, + "Number of free buffers"); +static int lofreebuffers; +SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, + "XXX Unused"); +static int hifreebuffers; +SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, + "XXX Complicatedly unused"); +static int getnewbufcalls; +SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, + "Number of calls to getnewbuf"); +static int getnewbufrestarts; +SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, + "Number of times getnewbuf has had to restart a buffer aquisition"); +static int flushbufqtarget = 100; +SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, + "Amount of work to do in flushbufqueues when helping bufdaemon"); +static long notbufdflashes; +SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, + "Number of dirty buffer flushes done by the bufdaemon helpers"); + +/* + * Wakeup point for bufdaemon, as well as indicator of whether it is already + * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it + * is idling. + */ +static int bd_request; + +/* + * Request for the buf daemon to write more buffers than is indicated by + * lodirtybuf. This may be necessary to push out excess dependencies or + * defragment the address space where a simple count of the number of dirty + * buffers is insufficient to characterize the demand for flushing them. + */ +static int bd_speedupreq; + +/* + * This lock synchronizes access to bd_request. + */ +static struct mtx bdlock; + +/* + * bogus page -- for I/O to/from partially complete buffers + * this is a temporary solution to the problem, but it is not + * really that bad. it would be better to split the buffer + * for input in the case of buffers partially already in memory, + * but the code is intricate enough already. + */ +vm_page_t bogus_page; + +/* + * Synchronization (sleep/wakeup) variable for active buffer space requests. + * Set when wait starts, cleared prior to wakeup(). + * Used in runningbufwakeup() and waitrunningbufspace(). + */ +static int runningbufreq; + +/* + * This lock protects the runningbufreq and synchronizes runningbufwakeup and + * waitrunningbufspace(). + */ +static struct mtx rbreqlock; + +/* + * Synchronization (sleep/wakeup) variable for buffer requests. + * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done + * by and/or. + * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), + * getnewbuf(), and getblk(). + */ +static int needsbuffer; + +/* + * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. + */ +static struct mtx nblock; + +/* + * Definitions for the buffer free lists. + */ +#define BUFFER_QUEUES 5 /* number of free buffer queues */ + +#define QUEUE_NONE 0 /* on no queue */ +#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ +#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ +#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ +#define QUEUE_EMPTY 4 /* empty buffer headers */ +#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ + +/* Queues for free buffers with various properties */ +static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; + +/* Lock for the bufqueues */ +static struct mtx bqlock; + +/* + * Single global constant for BUF_WMESG, to avoid getting multiple references. + * buf_wmesg is referred from macros. + */ +const char *buf_wmesg = BUF_WMESG; + +#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ +#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ +#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ +#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ + +#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ + defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) +static int +sysctl_bufspace(SYSCTL_HANDLER_ARGS) +{ + long lvalue; + int ivalue; + + if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) + return (sysctl_handle_long(oidp, arg1, arg2, req)); + lvalue = *(long *)arg1; + if (lvalue > INT_MAX) + /* On overflow, still write out a long to trigger ENOMEM. */ + return (sysctl_handle_long(oidp, &lvalue, 0, req)); + ivalue = lvalue; + return (sysctl_handle_int(oidp, &ivalue, 0, req)); +} +#endif + +#ifdef DIRECTIO +extern void ffs_rawread_setup(void); +#endif /* DIRECTIO */ +/* + * numdirtywakeup: + * + * If someone is blocked due to there being too many dirty buffers, + * and numdirtybuffers is now reasonable, wake them up. + */ + +static __inline void +numdirtywakeup(int level) +{ + + if (numdirtybuffers <= level) { + mtx_lock(&nblock); + if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { + needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; + wakeup(&needsbuffer); + } + mtx_unlock(&nblock); + } +} + +/* + * bufspacewakeup: + * + * Called when buffer space is potentially available for recovery. + * getnewbuf() will block on this flag when it is unable to free + * sufficient buffer space. Buffer space becomes recoverable when + * bp's get placed back in the queues. + */ + +static __inline void +bufspacewakeup(void) +{ + + /* + * If someone is waiting for BUF space, wake them up. Even + * though we haven't freed the kva space yet, the waiting + * process will be able to now. + */ + mtx_lock(&nblock); + if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { + needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; + wakeup(&needsbuffer); + } + mtx_unlock(&nblock); +} + +/* + * runningbufwakeup() - in-progress I/O accounting. + * + */ +void +runningbufwakeup(struct buf *bp) +{ + + if (bp->b_runningbufspace) { + atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); + bp->b_runningbufspace = 0; + mtx_lock(&rbreqlock); + if (runningbufreq && runningbufspace <= lorunningspace) { + runningbufreq = 0; + wakeup(&runningbufreq); + } + mtx_unlock(&rbreqlock); + } +} + +/* + * bufcountwakeup: + * + * Called when a buffer has been added to one of the free queues to + * account for the buffer and to wakeup anyone waiting for free buffers. + * This typically occurs when large amounts of metadata are being handled + * by the buffer cache ( else buffer space runs out first, usually ). + */ + +static __inline void +bufcountwakeup(struct buf *bp) +{ + int old; + + KASSERT((bp->b_vflags & BV_INFREECNT) == 0, + ("buf %p already counted as free", bp)); + if (bp->b_bufobj != NULL) + mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); + bp->b_vflags |= BV_INFREECNT; + old = atomic_fetchadd_int(&numfreebuffers, 1); + KASSERT(old >= 0 && old < nbuf, + ("numfreebuffers climbed to %d", old + 1)); + mtx_lock(&nblock); + if (needsbuffer) { + needsbuffer &= ~VFS_BIO_NEED_ANY; + if (numfreebuffers >= hifreebuffers) + needsbuffer &= ~VFS_BIO_NEED_FREE; + wakeup(&needsbuffer); + } + mtx_unlock(&nblock); +} + +/* + * waitrunningbufspace() + * + * runningbufspace is a measure of the amount of I/O currently + * running. This routine is used in async-write situations to + * prevent creating huge backups of pending writes to a device. + * Only asynchronous writes are governed by this function. + * + * Reads will adjust runningbufspace, but will not block based on it. + * The read load has a side effect of reducing the allowed write load. + * + * This does NOT turn an async write into a sync write. It waits + * for earlier writes to complete and generally returns before the + * caller's write has reached the device. + */ +void +waitrunningbufspace(void) +{ + + mtx_lock(&rbreqlock); + while (runningbufspace > hirunningspace) { + ++runningbufreq; + msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); + } + mtx_unlock(&rbreqlock); +} + + +/* + * vfs_buf_test_cache: + * + * Called when a buffer is extended. This function clears the B_CACHE + * bit if the newly extended portion of the buffer does not contain + * valid data. + */ +static __inline +void +vfs_buf_test_cache(struct buf *bp, + vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, + vm_page_t m) +{ + + VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); + if (bp->b_flags & B_CACHE) { + int base = (foff + off) & PAGE_MASK; + if (vm_page_is_valid(m, base, size) == 0) + bp->b_flags &= ~B_CACHE; + } +} + +/* Wake up the buffer daemon if necessary */ +static __inline +void +bd_wakeup(int dirtybuflevel) +{ + + mtx_lock(&bdlock); + if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { + bd_request = 1; + wakeup(&bd_request); + } + mtx_unlock(&bdlock); +} + +/* + * bd_speedup - speedup the buffer cache flushing code + */ + +void +bd_speedup(void) +{ + int needwake; + + mtx_lock(&bdlock); + needwake = 0; + if (bd_speedupreq == 0 || bd_request == 0) + needwake = 1; + bd_speedupreq = 1; + bd_request = 1; + if (needwake) + wakeup(&bd_request); + mtx_unlock(&bdlock); +} + +/* + * Calculating buffer cache scaling values and reserve space for buffer + * headers. This is called during low level kernel initialization and + * may be called more then once. We CANNOT write to the memory area + * being reserved at this time. + */ +caddr_t +kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) +{ + int tuned_nbuf; + long maxbuf; + + /* + * physmem_est is in pages. Convert it to kilobytes (assumes + * PAGE_SIZE is >= 1K) + */ + physmem_est = physmem_est * (PAGE_SIZE / 1024); + + /* + * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. + * For the first 64MB of ram nominally allocate sufficient buffers to + * cover 1/4 of our ram. Beyond the first 64MB allocate additional + * buffers to cover 1/10 of our ram over 64MB. When auto-sizing + * the buffer cache we limit the eventual kva reservation to + * maxbcache bytes. + * + * factor represents the 1/4 x ram conversion. + */ + if (nbuf == 0) { + int factor = 4 * BKVASIZE / 1024; + + nbuf = 50; + if (physmem_est > 4096) + nbuf += min((physmem_est - 4096) / factor, + 65536 / factor); + if (physmem_est > 65536) + nbuf += (physmem_est - 65536) * 2 / (factor * 5); + + if (maxbcache && nbuf > maxbcache / BKVASIZE) + nbuf = maxbcache / BKVASIZE; + tuned_nbuf = 1; + } else + tuned_nbuf = 0; + + /* XXX Avoid unsigned long overflows later on with maxbufspace. */ + maxbuf = (LONG_MAX / 3) / BKVASIZE; + if (nbuf > maxbuf) { + if (!tuned_nbuf) + printf("Warning: nbufs lowered from %d to %ld\n", nbuf, + maxbuf); + nbuf = maxbuf; + } + + /* + * swbufs are used as temporary holders for I/O, such as paging I/O. + * We have no less then 16 and no more then 256. + */ + nswbuf = max(min(nbuf/4, 256), 16); +#ifdef NSWBUF_MIN + if (nswbuf < NSWBUF_MIN) + nswbuf = NSWBUF_MIN; +#endif +#ifdef DIRECTIO + ffs_rawread_setup(); +#endif + + /* + * Reserve space for the buffer cache buffers + */ + swbuf = (void *)v; + v = (caddr_t)(swbuf + nswbuf); + buf = (void *)v; + v = (caddr_t)(buf + nbuf); + + return(v); +} + +/* Initialize the buffer subsystem. Called before use of any buffers. */ +void +bufinit(void) +{ + struct buf *bp; + int i; + + mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); + mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); + mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); + mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); + + /* next, make a null set of free lists */ + for (i = 0; i < BUFFER_QUEUES; i++) + TAILQ_INIT(&bufqueues[i]); + + /* finally, initialize each buffer header and stick on empty q */ + for (i = 0; i < nbuf; i++) { + bp = &buf[i]; + bzero(bp, sizeof *bp); + bp->b_flags = B_INVAL; /* we're just an empty header */ + bp->b_rcred = NOCRED; + bp->b_wcred = NOCRED; + bp->b_qindex = QUEUE_EMPTY; + bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ + bp->b_xflags = 0; + LIST_INIT(&bp->b_dep); + BUF_LOCKINIT(bp); + TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); + } + + /* + * maxbufspace is the absolute maximum amount of buffer space we are + * allowed to reserve in KVM and in real terms. The absolute maximum + * is nominally used by buf_daemon. hibufspace is the nominal maximum + * used by most other processes. The differential is required to + * ensure that buf_daemon is able to run when other processes might + * be blocked waiting for buffer space. + * + * maxbufspace is based on BKVASIZE. Allocating buffers larger then + * this may result in KVM fragmentation which is not handled optimally + * by the system. + */ + maxbufspace = (long)nbuf * BKVASIZE; + hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); + lobufspace = hibufspace - MAXBSIZE; + + /* + * Note: The 16 MiB upper limit for hirunningspace was chosen + * arbitrarily and may need further tuning. It corresponds to + * 128 outstanding write IO requests (if IO size is 128 KiB), + * which fits with many RAID controllers' tagged queuing limits. + * The lower 1 MiB limit is the historical upper limit for + * hirunningspace. + */ + hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), + 16 * 1024 * 1024), 1024 * 1024); + lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); + +/* + * Limit the amount of malloc memory since it is wired permanently into + * the kernel space. Even though this is accounted for in the buffer + * allocation, we don't want the malloced region to grow uncontrolled. + * The malloc scheme improves memory utilization significantly on average + * (small) directories. + */ + maxbufmallocspace = hibufspace / 20; + +/* + * Reduce the chance of a deadlock occuring by limiting the number + * of delayed-write dirty buffers we allow to stack up. + */ + hidirtybuffers = nbuf / 4 + 20; + dirtybufthresh = hidirtybuffers * 9 / 10; + numdirtybuffers = 0; +/* + * To support extreme low-memory systems, make sure hidirtybuffers cannot + * eat up all available buffer space. This occurs when our minimum cannot + * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming + * BKVASIZE'd buffers. + */ + while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { + hidirtybuffers >>= 1; + } + lodirtybuffers = hidirtybuffers / 2; + +/* + * Try to keep the number of free buffers in the specified range, + * and give special processes (e.g. like buf_daemon) access to an + * emergency reserve. + */ + lofreebuffers = nbuf / 18 + 5; + hifreebuffers = 2 * lofreebuffers; + numfreebuffers = nbuf; + + bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | + VM_ALLOC_NORMAL | VM_ALLOC_WIRED); +} + +/* + * bfreekva() - free the kva allocation for a buffer. + * + * Since this call frees up buffer space, we call bufspacewakeup(). + */ +static void +bfreekva(struct buf *bp) +{ + + if (bp->b_kvasize) { + atomic_add_int(&buffreekvacnt, 1); + atomic_subtract_long(&bufspace, bp->b_kvasize); + vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, + (vm_offset_t) bp->b_kvabase + bp->b_kvasize); + bp->b_kvasize = 0; + bufspacewakeup(); + } +} + +/* + * bremfree: + * + * Mark the buffer for removal from the appropriate free list in brelse. + * + */ +void +bremfree(struct buf *bp) +{ + int old; + + CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + KASSERT((bp->b_flags & B_REMFREE) == 0, + ("bremfree: buffer %p already marked for delayed removal.", bp)); + KASSERT(bp->b_qindex != QUEUE_NONE, + ("bremfree: buffer %p not on a queue.", bp)); + BUF_ASSERT_HELD(bp); + + bp->b_flags |= B_REMFREE; + /* Fixup numfreebuffers count. */ + if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { + KASSERT((bp->b_vflags & BV_INFREECNT) != 0, + ("buf %p not counted in numfreebuffers", bp)); + if (bp->b_bufobj != NULL) + mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); + bp->b_vflags &= ~BV_INFREECNT; + old = atomic_fetchadd_int(&numfreebuffers, -1); + KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); + } +} + +/* + * bremfreef: + * + * Force an immediate removal from a free list. Used only in nfs when + * it abuses the b_freelist pointer. + */ +void +bremfreef(struct buf *bp) +{ + mtx_lock(&bqlock); + bremfreel(bp); + mtx_unlock(&bqlock); +} + +/* + * bremfreel: + * + * Removes a buffer from the free list, must be called with the + * bqlock held. + */ +static void +bremfreel(struct buf *bp) +{ + int old; + + CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", + bp, bp->b_vp, bp->b_flags); + KASSERT(bp->b_qindex != QUEUE_NONE, + ("bremfreel: buffer %p not on a queue.", bp)); + BUF_ASSERT_HELD(bp); + mtx_assert(&bqlock, MA_OWNED); + + TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); + bp->b_qindex = QUEUE_NONE; + /* + * If this was a delayed bremfree() we only need to remove the buffer + * from the queue and return the stats are already done. + */ + if (bp->b_flags & B_REMFREE) { + bp->b_flags &= ~B_REMFREE; + return; + } + /* + * Fixup numfreebuffers count. If the buffer is invalid or not + * delayed-write, the buffer was free and we must decrement + * numfreebuffers. + */ + if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { + KASSERT((bp->b_vflags & BV_INFREECNT) != 0, + ("buf %p not counted in numfreebuffers", bp)); + if (bp->b_bufobj != NULL) + mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); + bp->b_vflags &= ~BV_INFREECNT; + old = atomic_fetchadd_int(&numfreebuffers, -1); + KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); + } +} + +/* + * Attempt to initiate asynchronous I/O on read-ahead blocks. We must + * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, + * the buffer is valid and we do not have to do anything. + */ +void +breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, + int cnt, struct ucred * cred) +{ + struct buf *rabp; + int i; + + for (i = 0; i < cnt; i++, rablkno++, rabsize++) { + if (inmem(vp, *rablkno)) + continue; + rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); + + if ((rabp->b_flags & B_CACHE) == 0) { + if (!TD_IS_IDLETHREAD(curthread)) + curthread->td_ru.ru_inblock++; + rabp->b_flags |= B_ASYNC; + rabp->b_flags &= ~B_INVAL; + rabp->b_ioflags &= ~BIO_ERROR; + rabp->b_iocmd = BIO_READ; + if (rabp->b_rcred == NOCRED && cred != NOCRED) + rabp->b_rcred = crhold(cred); + vfs_busy_pages(rabp, 0); + BUF_KERNPROC(rabp); + rabp->b_iooffset = dbtob(rabp->b_blkno); + bstrategy(rabp); + } else { + brelse(rabp); + } + } +} + +/* + * Entry point for bread() and breadn() via #defines in sys/buf.h. + * + * Get a buffer with the specified data. Look in the cache first. We + * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE + * is set, the buffer is valid and we do not have to do anything, see + * getblk(). Also starts asynchronous I/O on read-ahead blocks. + */ +int +breadn_flags(struct vnode * vp, daddr_t blkno, int size, + daddr_t * rablkno, int *rabsize, int cnt, + struct ucred * cred, int flags, struct buf **bpp) +{ + struct buf *bp; + int rv = 0, readwait = 0; + + CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); + /* + * Can only return NULL if GB_LOCK_NOWAIT flag is specified. + */ + *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); + if (bp == NULL) + return (EBUSY); + + /* if not found in cache, do some I/O */ + if ((bp->b_flags & B_CACHE) == 0) { + if (!TD_IS_IDLETHREAD(curthread)) + curthread->td_ru.ru_inblock++; + bp->b_iocmd = BIO_READ; + bp->b_flags &= ~B_INVAL; + bp->b_ioflags &= ~BIO_ERROR; + if (bp->b_rcred == NOCRED && cred != NOCRED) + bp->b_rcred = crhold(cred); + vfs_busy_pages(bp, 0); + bp->b_iooffset = dbtob(bp->b_blkno); + bstrategy(bp); + ++readwait; + } + + breada(vp, rablkno, rabsize, cnt, cred); + + if (readwait) { + rv = bufwait(bp); + } + return (rv); +} + +/* + * Write, release buffer on completion. (Done by iodone + * if async). Do not bother writing anything if the buffer + * is invalid. + * + * Note that we set B_CACHE here, indicating that buffer is + * fully valid and thus cacheable. This is true even of NFS + * now so we set it generally. This could be set either here + * or in biodone() since the I/O is synchronous. We put it + * here. + */ +int +bufwrite(struct buf *bp) +{ + int oldflags; + struct vnode *vp; + int vp_md; + + CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + if (bp->b_flags & B_INVAL) { + brelse(bp); + return (0); + } + + oldflags = bp->b_flags; + + BUF_ASSERT_HELD(bp); + + if (bp->b_pin_count > 0) + bunpin_wait(bp); + + KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), + ("FFS background buffer should not get here %p", bp)); + + vp = bp->b_vp; + if (vp) + vp_md = vp->v_vflag & VV_MD; + else + vp_md = 0; + + /* Mark the buffer clean */ + bundirty(bp); + + bp->b_flags &= ~B_DONE; + bp->b_ioflags &= ~BIO_ERROR; + bp->b_flags |= B_CACHE; + bp->b_iocmd = BIO_WRITE; + + bufobj_wref(bp->b_bufobj); + vfs_busy_pages(bp, 1); + + /* + * Normal bwrites pipeline writes + */ + bp->b_runningbufspace = bp->b_bufsize; + atomic_add_long(&runningbufspace, bp->b_runningbufspace); + + if (!TD_IS_IDLETHREAD(curthread)) + curthread->td_ru.ru_oublock++; + if (oldflags & B_ASYNC) + BUF_KERNPROC(bp); + bp->b_iooffset = dbtob(bp->b_blkno); + bstrategy(bp); + + if ((oldflags & B_ASYNC) == 0) { + int rtval = bufwait(bp); + brelse(bp); + return (rtval); + } else { + /* + * don't allow the async write to saturate the I/O + * system. We will not deadlock here because + * we are blocking waiting for I/O that is already in-progress + * to complete. We do not block here if it is the update + * or syncer daemon trying to clean up as that can lead + * to deadlock. + */ + if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) + waitrunningbufspace(); + } + + return (0); +} + +void +bufbdflush(struct bufobj *bo, struct buf *bp) +{ + struct buf *nbp; + + if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { + (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); + altbufferflushes++; + } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { + BO_LOCK(bo); + /* + * Try to find a buffer to flush. + */ + TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { + if ((nbp->b_vflags & BV_BKGRDINPROG) || + BUF_LOCK(nbp, + LK_EXCLUSIVE | LK_NOWAIT, NULL)) + continue; + if (bp == nbp) + panic("bdwrite: found ourselves"); + BO_UNLOCK(bo); + /* Don't countdeps with the bo lock held. */ + if (buf_countdeps(nbp, 0)) { + BO_LOCK(bo); + BUF_UNLOCK(nbp); + continue; + } + if (nbp->b_flags & B_CLUSTEROK) { + vfs_bio_awrite(nbp); + } else { + bremfree(nbp); + bawrite(nbp); + } + dirtybufferflushes++; + break; + } + if (nbp == NULL) + BO_UNLOCK(bo); + } +} + +/* + * Delayed write. (Buffer is marked dirty). Do not bother writing + * anything if the buffer is marked invalid. + * + * Note that since the buffer must be completely valid, we can safely + * set B_CACHE. In fact, we have to set B_CACHE here rather then in + * biodone() in order to prevent getblk from writing the buffer + * out synchronously. + */ +void +bdwrite(struct buf *bp) +{ + struct thread *td = curthread; + struct vnode *vp; + struct bufobj *bo; + + CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); + BUF_ASSERT_HELD(bp); + + if (bp->b_flags & B_INVAL) { + brelse(bp); + return; + } + + /* + * If we have too many dirty buffers, don't create any more. + * If we are wildly over our limit, then force a complete + * cleanup. Otherwise, just keep the situation from getting + * out of control. Note that we have to avoid a recursive + * disaster and not try to clean up after our own cleanup! + */ + vp = bp->b_vp; + bo = bp->b_bufobj; + if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { + td->td_pflags |= TDP_INBDFLUSH; + BO_BDFLUSH(bo, bp); + td->td_pflags &= ~TDP_INBDFLUSH; + } else + recursiveflushes++; + + bdirty(bp); + /* + * Set B_CACHE, indicating that the buffer is fully valid. This is + * true even of NFS now. + */ + bp->b_flags |= B_CACHE; + + /* + * This bmap keeps the system from needing to do the bmap later, + * perhaps when the system is attempting to do a sync. Since it + * is likely that the indirect block -- or whatever other datastructure + * that the filesystem needs is still in memory now, it is a good + * thing to do this. Note also, that if the pageout daemon is + * requesting a sync -- there might not be enough memory to do + * the bmap then... So, this is important to do. + */ + if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { + VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); + } + + /* + * Set the *dirty* buffer range based upon the VM system dirty + * pages. + * + * Mark the buffer pages as clean. We need to do this here to + * satisfy the vnode_pager and the pageout daemon, so that it + * thinks that the pages have been "cleaned". Note that since + * the pages are in a delayed write buffer -- the VFS layer + * "will" see that the pages get written out on the next sync, + * or perhaps the cluster will be completed. + */ + vfs_clean_pages_dirty_buf(bp); + bqrelse(bp); + + /* + * Wakeup the buffer flushing daemon if we have a lot of dirty + * buffers (midpoint between our recovery point and our stall + * point). + */ + bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); + + /* + * note: we cannot initiate I/O from a bdwrite even if we wanted to, + * due to the softdep code. + */ +} + +/* + * bdirty: + * + * Turn buffer into delayed write request. We must clear BIO_READ and + * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to + * itself to properly update it in the dirty/clean lists. We mark it + * B_DONE to ensure that any asynchronization of the buffer properly + * clears B_DONE ( else a panic will occur later ). + * + * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which + * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() + * should only be called if the buffer is known-good. + * + * Since the buffer is not on a queue, we do not update the numfreebuffers + * count. + * + * The buffer must be on QUEUE_NONE. + */ +void +bdirty(struct buf *bp) +{ + + CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", + bp, bp->b_vp, bp->b_flags); + KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); + KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, + ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); + BUF_ASSERT_HELD(bp); + bp->b_flags &= ~(B_RELBUF); + bp->b_iocmd = BIO_WRITE; + + if ((bp->b_flags & B_DELWRI) == 0) { + bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; + reassignbuf(bp); + atomic_add_int(&numdirtybuffers, 1); + bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); + } +} + +/* + * bundirty: + * + * Clear B_DELWRI for buffer. + * + * Since the buffer is not on a queue, we do not update the numfreebuffers + * count. + * + * The buffer must be on QUEUE_NONE. + */ + +void +bundirty(struct buf *bp) +{ + + CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); + KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, + ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); + BUF_ASSERT_HELD(bp); + + if (bp->b_flags & B_DELWRI) { + bp->b_flags &= ~B_DELWRI; + reassignbuf(bp); + atomic_subtract_int(&numdirtybuffers, 1); + numdirtywakeup(lodirtybuffers); + } + /* + * Since it is now being written, we can clear its deferred write flag. + */ + bp->b_flags &= ~B_DEFERRED; +} + +/* + * bawrite: + * + * Asynchronous write. Start output on a buffer, but do not wait for + * it to complete. The buffer is released when the output completes. + * + * bwrite() ( or the VOP routine anyway ) is responsible for handling + * B_INVAL buffers. Not us. + */ +void +bawrite(struct buf *bp) +{ + + bp->b_flags |= B_ASYNC; + (void) bwrite(bp); +} + +/* + * bwillwrite: + * + * Called prior to the locking of any vnodes when we are expecting to + * write. We do not want to starve the buffer cache with too many + * dirty buffers so we block here. By blocking prior to the locking + * of any vnodes we attempt to avoid the situation where a locked vnode + * prevents the various system daemons from flushing related buffers. + */ + +void +bwillwrite(void) +{ + + if (numdirtybuffers >= hidirtybuffers) { + mtx_lock(&nblock); + while (numdirtybuffers >= hidirtybuffers) { + bd_wakeup(1); + needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; + msleep(&needsbuffer, &nblock, + (PRIBIO + 4), "flswai", 0); + } + mtx_unlock(&nblock); + } +} + +/* + * Return true if we have too many dirty buffers. + */ +int +buf_dirty_count_severe(void) +{ + + return(numdirtybuffers >= hidirtybuffers); +} + +static __noinline int +buf_vm_page_count_severe(void) +{ + + KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); + + return vm_page_count_severe(); +} + +/* + * brelse: + * + * Release a busy buffer and, if requested, free its resources. The + * buffer will be stashed in the appropriate bufqueue[] allowing it + * to be accessed later as a cache entity or reused for other purposes. + */ +void +brelse(struct buf *bp) +{ + CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", + bp, bp->b_vp, bp->b_flags); + KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), + ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); + + if (bp->b_flags & B_MANAGED) { + bqrelse(bp); + return; + } + + if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && + bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { + /* + * Failed write, redirty. Must clear BIO_ERROR to prevent + * pages from being scrapped. If the error is anything + * other than an I/O error (EIO), assume that retrying + * is futile. + */ + bp->b_ioflags &= ~BIO_ERROR; + bdirty(bp); + } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || + (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { + /* + * Either a failed I/O or we were asked to free or not + * cache the buffer. + */ + bp->b_flags |= B_INVAL; + if (!LIST_EMPTY(&bp->b_dep)) + buf_deallocate(bp); + if (bp->b_flags & B_DELWRI) { + atomic_subtract_int(&numdirtybuffers, 1); + numdirtywakeup(lodirtybuffers); + } + bp->b_flags &= ~(B_DELWRI | B_CACHE); + if ((bp->b_flags & B_VMIO) == 0) { + if (bp->b_bufsize) + allocbuf(bp, 0); + if (bp->b_vp) + brelvp(bp); + } + } + + /* + * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() + * is called with B_DELWRI set, the underlying pages may wind up + * getting freed causing a previous write (bdwrite()) to get 'lost' + * because pages associated with a B_DELWRI bp are marked clean. + * + * We still allow the B_INVAL case to call vfs_vmio_release(), even + * if B_DELWRI is set. + * + * If B_DELWRI is not set we may have to set B_RELBUF if we are low + * on pages to return pages to the VM page queues. + */ + if (bp->b_flags & B_DELWRI) + bp->b_flags &= ~B_RELBUF; + else if (buf_vm_page_count_severe()) { + /* + * The locking of the BO_LOCK is not necessary since + * BKGRDINPROG cannot be set while we hold the buf + * lock, it can only be cleared if it is already + * pending. + */ + if (bp->b_vp) { + if (!(bp->b_vflags & BV_BKGRDINPROG)) + bp->b_flags |= B_RELBUF; + } else + bp->b_flags |= B_RELBUF; + } + + /* + * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer + * constituted, not even NFS buffers now. Two flags effect this. If + * B_INVAL, the struct buf is invalidated but the VM object is kept + * around ( i.e. so it is trivial to reconstitute the buffer later ). + * + * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be + * invalidated. BIO_ERROR cannot be set for a failed write unless the + * buffer is also B_INVAL because it hits the re-dirtying code above. + * + * Normally we can do this whether a buffer is B_DELWRI or not. If + * the buffer is an NFS buffer, it is tracking piecemeal writes or + * the commit state and we cannot afford to lose the buffer. If the + * buffer has a background write in progress, we need to keep it + * around to prevent it from being reconstituted and starting a second + * background write. + */ + if ((bp->b_flags & B_VMIO) + && !(bp->b_vp->v_mount != NULL && + (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && + !vn_isdisk(bp->b_vp, NULL) && + (bp->b_flags & B_DELWRI)) + ) { + + int i, j, resid; + vm_page_t m; + off_t foff; + vm_pindex_t poff; + vm_object_t obj; + + obj = bp->b_bufobj->bo_object; + + /* + * Get the base offset and length of the buffer. Note that + * in the VMIO case if the buffer block size is not + * page-aligned then b_data pointer may not be page-aligned. + * But our b_pages[] array *IS* page aligned. + * + * block sizes less then DEV_BSIZE (usually 512) are not + * supported due to the page granularity bits (m->valid, + * m->dirty, etc...). + * + * See man buf(9) for more information + */ + resid = bp->b_bufsize; + foff = bp->b_offset; + VM_OBJECT_LOCK(obj); + for (i = 0; i < bp->b_npages; i++) { + int had_bogus = 0; + + m = bp->b_pages[i]; + + /* + * If we hit a bogus page, fixup *all* the bogus pages + * now. + */ + if (m == bogus_page) { + poff = OFF_TO_IDX(bp->b_offset); + had_bogus = 1; + + for (j = i; j < bp->b_npages; j++) { + vm_page_t mtmp; + mtmp = bp->b_pages[j]; + if (mtmp == bogus_page) { + mtmp = vm_page_lookup(obj, poff + j); + if (!mtmp) { + panic("brelse: page missing\n"); + } + bp->b_pages[j] = mtmp; + } + } + + if ((bp->b_flags & B_INVAL) == 0) { + pmap_qenter( + trunc_page((vm_offset_t)bp->b_data), + bp->b_pages, bp->b_npages); + } + m = bp->b_pages[i]; + } + if ((bp->b_flags & B_NOCACHE) || + (bp->b_ioflags & BIO_ERROR && + bp->b_iocmd == BIO_READ)) { + int poffset = foff & PAGE_MASK; + int presid = resid > (PAGE_SIZE - poffset) ? + (PAGE_SIZE - poffset) : resid; + + KASSERT(presid >= 0, ("brelse: extra page")); + vm_page_set_invalid(m, poffset, presid); + if (had_bogus) + printf("avoided corruption bug in bogus_page/brelse code\n"); + } + resid -= PAGE_SIZE - (foff & PAGE_MASK); + foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; + } + VM_OBJECT_UNLOCK(obj); + if (bp->b_flags & (B_INVAL | B_RELBUF)) + vfs_vmio_release(bp); + + } else if (bp->b_flags & B_VMIO) { + + if (bp->b_flags & (B_INVAL | B_RELBUF)) { + vfs_vmio_release(bp); + } + + } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { + if (bp->b_bufsize != 0) + allocbuf(bp, 0); + if (bp->b_vp != NULL) + brelvp(bp); + } + + if (BUF_LOCKRECURSED(bp)) { + /* do not release to free list */ + BUF_UNLOCK(bp); + return; + } + + /* enqueue */ + mtx_lock(&bqlock); + /* Handle delayed bremfree() processing. */ + if (bp->b_flags & B_REMFREE) { + struct bufobj *bo; + + bo = bp->b_bufobj; + if (bo != NULL) + BO_LOCK(bo); + bremfreel(bp); + if (bo != NULL) + BO_UNLOCK(bo); + } + if (bp->b_qindex != QUEUE_NONE) + panic("brelse: free buffer onto another queue???"); + + /* + * If the buffer has junk contents signal it and eventually + * clean up B_DELWRI and diassociate the vnode so that gbincore() + * doesn't find it. + */ + if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || + (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) + bp->b_flags |= B_INVAL; + if (bp->b_flags & B_INVAL) { + if (bp->b_flags & B_DELWRI) + bundirty(bp); + if (bp->b_vp) + brelvp(bp); + } + + /* buffers with no memory */ + if (bp->b_bufsize == 0) { + bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); + if (bp->b_vflags & BV_BKGRDINPROG) + panic("losing buffer 1"); + if (bp->b_kvasize) { + bp->b_qindex = QUEUE_EMPTYKVA; + } else { + bp->b_qindex = QUEUE_EMPTY; + } + TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); + /* buffers with junk contents */ + } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || + (bp->b_ioflags & BIO_ERROR)) { + bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); + if (bp->b_vflags & BV_BKGRDINPROG) + panic("losing buffer 2"); + bp->b_qindex = QUEUE_CLEAN; + TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); + /* remaining buffers */ + } else { + if (bp->b_flags & B_DELWRI) + bp->b_qindex = QUEUE_DIRTY; + else + bp->b_qindex = QUEUE_CLEAN; + if (bp->b_flags & B_AGE) + TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); + else + TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); + } + mtx_unlock(&bqlock); + + /* + * Fixup numfreebuffers count. The bp is on an appropriate queue + * unless locked. We then bump numfreebuffers if it is not B_DELWRI. + * We've already handled the B_INVAL case ( B_DELWRI will be clear + * if B_INVAL is set ). + */ + + if (!(bp->b_flags & B_DELWRI)) { + struct bufobj *bo; + + bo = bp->b_bufobj; + if (bo != NULL) + BO_LOCK(bo); + bufcountwakeup(bp); + if (bo != NULL) + BO_UNLOCK(bo); + } + + /* + * Something we can maybe free or reuse + */ + if (bp->b_bufsize || bp->b_kvasize) + bufspacewakeup(); + + bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); + if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) + panic("brelse: not dirty"); + /* unlock */ + BUF_UNLOCK(bp); +} + +/* + * Release a buffer back to the appropriate queue but do not try to free + * it. The buffer is expected to be used again soon. + * + * bqrelse() is used by bdwrite() to requeue a delayed write, and used by + * biodone() to requeue an async I/O on completion. It is also used when + * known good buffers need to be requeued but we think we may need the data + * again soon. + * + * XXX we should be able to leave the B_RELBUF hint set on completion. + */ +void +bqrelse(struct buf *bp) +{ + struct bufobj *bo; + + CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), + ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); + + if (BUF_LOCKRECURSED(bp)) { + /* do not release to free list */ + BUF_UNLOCK(bp); + return; + } + + bo = bp->b_bufobj; + if (bp->b_flags & B_MANAGED) { + if (bp->b_flags & B_REMFREE) { + mtx_lock(&bqlock); + if (bo != NULL) + BO_LOCK(bo); + bremfreel(bp); + if (bo != NULL) + BO_UNLOCK(bo); + mtx_unlock(&bqlock); + } + bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); + BUF_UNLOCK(bp); + return; + } + + mtx_lock(&bqlock); + /* Handle delayed bremfree() processing. */ + if (bp->b_flags & B_REMFREE) { + if (bo != NULL) + BO_LOCK(bo); + bremfreel(bp); + if (bo != NULL) + BO_UNLOCK(bo); + } + if (bp->b_qindex != QUEUE_NONE) + panic("bqrelse: free buffer onto another queue???"); + /* buffers with stale but valid contents */ + if (bp->b_flags & B_DELWRI) { + bp->b_qindex = QUEUE_DIRTY; + TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); + } else { + /* + * The locking of the BO_LOCK for checking of the + * BV_BKGRDINPROG is not necessary since the + * BV_BKGRDINPROG cannot be set while we hold the buf + * lock, it can only be cleared if it is already + * pending. + */ + if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { + bp->b_qindex = QUEUE_CLEAN; + TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, + b_freelist); + } else { + /* + * We are too low on memory, we have to try to free + * the buffer (most importantly: the wired pages + * making up its backing store) *now*. + */ + mtx_unlock(&bqlock); + brelse(bp); + return; + } + } + mtx_unlock(&bqlock); + + if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) { + if (bo != NULL) + BO_LOCK(bo); + bufcountwakeup(bp); + if (bo != NULL) + BO_UNLOCK(bo); + } + + /* + * Something we can maybe free or reuse. + */ + if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) + bufspacewakeup(); + + bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); + if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) + panic("bqrelse: not dirty"); + /* unlock */ + BUF_UNLOCK(bp); +} + +/* Give pages used by the bp back to the VM system (where possible) */ +static void +vfs_vmio_release(struct buf *bp) +{ + int i; + vm_page_t m; + + pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); + VM_OBJECT_LOCK(bp->b_bufobj->bo_object); + for (i = 0; i < bp->b_npages; i++) { + m = bp->b_pages[i]; + bp->b_pages[i] = NULL; + /* + * In order to keep page LRU ordering consistent, put + * everything on the inactive queue. + */ + vm_page_lock(m); + vm_page_unwire(m, 0); + /* + * We don't mess with busy pages, it is + * the responsibility of the process that + * busied the pages to deal with them. + */ + if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && + m->wire_count == 0) { + /* + * Might as well free the page if we can and it has + * no valid data. We also free the page if the + * buffer was used for direct I/O + */ + if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { + vm_page_free(m); + } else if (bp->b_flags & B_DIRECT) { + vm_page_try_to_free(m); + } else if (buf_vm_page_count_severe()) { + vm_page_try_to_cache(m); + } + } + vm_page_unlock(m); + } + VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); + + if (bp->b_bufsize) { + bufspacewakeup(); + bp->b_bufsize = 0; + } + bp->b_npages = 0; + bp->b_flags &= ~B_VMIO; + if (bp->b_vp) + brelvp(bp); +} + +/* + * Check to see if a block at a particular lbn is available for a clustered + * write. + */ +static int +vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) +{ + struct buf *bpa; + int match; + + match = 0; + + /* If the buf isn't in core skip it */ + if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) + return (0); + + /* If the buf is busy we don't want to wait for it */ + if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) + return (0); + + /* Only cluster with valid clusterable delayed write buffers */ + if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != + (B_DELWRI | B_CLUSTEROK)) + goto done; + + if (bpa->b_bufsize != size) + goto done; + + /* + * Check to see if it is in the expected place on disk and that the + * block has been mapped. + */ + if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) + match = 1; +done: + BUF_UNLOCK(bpa); + return (match); +} + +/* + * vfs_bio_awrite: + * + * Implement clustered async writes for clearing out B_DELWRI buffers. + * This is much better then the old way of writing only one buffer at + * a time. Note that we may not be presented with the buffers in the + * correct order, so we search for the cluster in both directions. + */ +int +vfs_bio_awrite(struct buf *bp) +{ + struct bufobj *bo; + int i; + int j; + daddr_t lblkno = bp->b_lblkno; + struct vnode *vp = bp->b_vp; + int ncl; + int nwritten; + int size; + int maxcl; + + bo = &vp->v_bufobj; + /* + * right now we support clustered writing only to regular files. If + * we find a clusterable block we could be in the middle of a cluster + * rather then at the beginning. + */ + if ((vp->v_type == VREG) && + (vp->v_mount != 0) && /* Only on nodes that have the size info */ + (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { + + size = vp->v_mount->mnt_stat.f_iosize; + maxcl = MAXPHYS / size; + + BO_LOCK(bo); + for (i = 1; i < maxcl; i++) + if (vfs_bio_clcheck(vp, size, lblkno + i, + bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) + break; + + for (j = 1; i + j <= maxcl && j <= lblkno; j++) + if (vfs_bio_clcheck(vp, size, lblkno - j, + bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) + break; + BO_UNLOCK(bo); + --j; + ncl = i + j; + /* + * this is a possible cluster write + */ + if (ncl != 1) { + BUF_UNLOCK(bp); + nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); + return nwritten; + } + } + bremfree(bp); + bp->b_flags |= B_ASYNC; + /* + * default (old) behavior, writing out only one block + * + * XXX returns b_bufsize instead of b_bcount for nwritten? + */ + nwritten = bp->b_bufsize; + (void) bwrite(bp); + + return nwritten; +} + +/* + * getnewbuf: + * + * Find and initialize a new buffer header, freeing up existing buffers + * in the bufqueues as necessary. The new buffer is returned locked. + * + * Important: B_INVAL is not set. If the caller wishes to throw the + * buffer away, the caller must set B_INVAL prior to calling brelse(). + * + * We block if: + * We have insufficient buffer headers + * We have insufficient buffer space + * buffer_map is too fragmented ( space reservation fails ) + * If we have to flush dirty buffers ( but we try to avoid this ) + * + * To avoid VFS layer recursion we do not flush dirty buffers ourselves. + * Instead we ask the buf daemon to do it for us. We attempt to + * avoid piecemeal wakeups of the pageout daemon. + */ + +static struct buf * +getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, + int gbflags) +{ + struct thread *td; + struct buf *bp; + struct buf *nbp; + int defrag = 0; + int nqindex; + static int flushingbufs; + + td = curthread; + /* + * We can't afford to block since we might be holding a vnode lock, + * which may prevent system daemons from running. We deal with + * low-memory situations by proactively returning memory and running + * async I/O rather then sync I/O. + */ + atomic_add_int(&getnewbufcalls, 1); + atomic_subtract_int(&getnewbufrestarts, 1); +restart: + atomic_add_int(&getnewbufrestarts, 1); + + /* + * Setup for scan. If we do not have enough free buffers, + * we setup a degenerate case that immediately fails. Note + * that if we are specially marked process, we are allowed to + * dip into our reserves. + * + * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN + * + * We start with EMPTYKVA. If the list is empty we backup to EMPTY. + * However, there are a number of cases (defragging, reusing, ...) + * where we cannot backup. + */ + mtx_lock(&bqlock); + nqindex = QUEUE_EMPTYKVA; + nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); + + if (nbp == NULL) { + /* + * If no EMPTYKVA buffers and we are either + * defragging or reusing, locate a CLEAN buffer + * to free or reuse. If bufspace useage is low + * skip this step so we can allocate a new buffer. + */ + if (defrag || bufspace >= lobufspace) { + nqindex = QUEUE_CLEAN; + nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); + } + + /* + * If we could not find or were not allowed to reuse a + * CLEAN buffer, check to see if it is ok to use an EMPTY + * buffer. We can only use an EMPTY buffer if allocating + * its KVA would not otherwise run us out of buffer space. + */ + if (nbp == NULL && defrag == 0 && + bufspace + maxsize < hibufspace) { + nqindex = QUEUE_EMPTY; + nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); + } + } + + /* + * Run scan, possibly freeing data and/or kva mappings on the fly + * depending. + */ + + while ((bp = nbp) != NULL) { + int qindex = nqindex; + + /* + * Calculate next bp ( we can only use it if we do not block + * or do other fancy things ). + */ + if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { + switch(qindex) { + case QUEUE_EMPTY: + nqindex = QUEUE_EMPTYKVA; + if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) + break; + /* FALLTHROUGH */ + case QUEUE_EMPTYKVA: + nqindex = QUEUE_CLEAN; + if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) + break; + /* FALLTHROUGH */ + case QUEUE_CLEAN: + /* + * nbp is NULL. + */ + break; + } + } + /* + * If we are defragging then we need a buffer with + * b_kvasize != 0. XXX this situation should no longer + * occur, if defrag is non-zero the buffer's b_kvasize + * should also be non-zero at this point. XXX + */ + if (defrag && bp->b_kvasize == 0) { + printf("Warning: defrag empty buffer %p\n", bp); + continue; + } + + /* + * Start freeing the bp. This is somewhat involved. nbp + * remains valid only for QUEUE_EMPTY[KVA] bp's. + */ + if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) + continue; + if (bp->b_vp) { + BO_LOCK(bp->b_bufobj); + if (bp->b_vflags & BV_BKGRDINPROG) { + BO_UNLOCK(bp->b_bufobj); + BUF_UNLOCK(bp); + continue; + } + BO_UNLOCK(bp->b_bufobj); + } + CTR6(KTR_BUF, + "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " + "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, + bp->b_kvasize, bp->b_bufsize, qindex); + + /* + * Sanity Checks + */ + KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); + + /* + * Note: we no longer distinguish between VMIO and non-VMIO + * buffers. + */ + + KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); + + if (bp->b_bufobj != NULL) + BO_LOCK(bp->b_bufobj); + bremfreel(bp); + if (bp->b_bufobj != NULL) + BO_UNLOCK(bp->b_bufobj); + mtx_unlock(&bqlock); + + if (qindex == QUEUE_CLEAN) { + if (bp->b_flags & B_VMIO) { + bp->b_flags &= ~B_ASYNC; + vfs_vmio_release(bp); + } + if (bp->b_vp) + brelvp(bp); + } + + /* + * NOTE: nbp is now entirely invalid. We can only restart + * the scan from this point on. + * + * Get the rest of the buffer freed up. b_kva* is still + * valid after this operation. + */ + + if (bp->b_rcred != NOCRED) { + crfree(bp->b_rcred); + bp->b_rcred = NOCRED; + } + if (bp->b_wcred != NOCRED) { + crfree(bp->b_wcred); + bp->b_wcred = NOCRED; + } + if (!LIST_EMPTY(&bp->b_dep)) + buf_deallocate(bp); + if (bp->b_vflags & BV_BKGRDINPROG) + panic("losing buffer 3"); + KASSERT(bp->b_vp == NULL, + ("bp: %p still has vnode %p. qindex: %d", + bp, bp->b_vp, qindex)); + KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, + ("bp: %p still on a buffer list. xflags %X", + bp, bp->b_xflags)); + + if (bp->b_bufsize) + allocbuf(bp, 0); + + bp->b_flags = 0; + bp->b_ioflags = 0; + bp->b_xflags = 0; + KASSERT((bp->b_vflags & BV_INFREECNT) == 0, + ("buf %p still counted as free?", bp)); + bp->b_vflags = 0; + bp->b_vp = NULL; + bp->b_blkno = bp->b_lblkno = 0; + bp->b_offset = NOOFFSET; + bp->b_iodone = 0; + bp->b_error = 0; + bp->b_resid = 0; + bp->b_bcount = 0; + bp->b_npages = 0; + bp->b_dirtyoff = bp->b_dirtyend = 0; + bp->b_bufobj = NULL; + bp->b_pin_count = 0; + bp->b_fsprivate1 = NULL; + bp->b_fsprivate2 = NULL; + bp->b_fsprivate3 = NULL; + + LIST_INIT(&bp->b_dep); + + /* + * If we are defragging then free the buffer. + */ + if (defrag) { + bp->b_flags |= B_INVAL; + bfreekva(bp); + brelse(bp); + defrag = 0; + goto restart; + } + + /* + * Notify any waiters for the buffer lock about + * identity change by freeing the buffer. + */ + if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { + bp->b_flags |= B_INVAL; + bfreekva(bp); + brelse(bp); + goto restart; + } + + /* + * If we are overcomitted then recover the buffer and its + * KVM space. This occurs in rare situations when multiple + * processes are blocked in getnewbuf() or allocbuf(). + */ + if (bufspace >= hibufspace) + flushingbufs = 1; + if (flushingbufs && bp->b_kvasize != 0) { + bp->b_flags |= B_INVAL; + bfreekva(bp); + brelse(bp); + goto restart; + } + if (bufspace < lobufspace) + flushingbufs = 0; + break; + } + + /* + * If we exhausted our list, sleep as appropriate. We may have to + * wakeup various daemons and write out some dirty buffers. + * + * Generally we are sleeping due to insufficient buffer space. + */ + + if (bp == NULL) { + int flags, norunbuf; + char *waitmsg; + int fl; + + if (defrag) { + flags = VFS_BIO_NEED_BUFSPACE; + waitmsg = "nbufkv"; + } else if (bufspace >= hibufspace) { + waitmsg = "nbufbs"; + flags = VFS_BIO_NEED_BUFSPACE; + } else { + waitmsg = "newbuf"; + flags = VFS_BIO_NEED_ANY; + } + mtx_lock(&nblock); + needsbuffer |= flags; + mtx_unlock(&nblock); + mtx_unlock(&bqlock); + + bd_speedup(); /* heeeelp */ + if (gbflags & GB_NOWAIT_BD) + return (NULL); + + mtx_lock(&nblock); + while (needsbuffer & flags) { + if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { + mtx_unlock(&nblock); + /* + * getblk() is called with a vnode + * locked, and some majority of the + * dirty buffers may as well belong to + * the vnode. Flushing the buffers + * there would make a progress that + * cannot be achieved by the + * buf_daemon, that cannot lock the + * vnode. + */ + norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | + (td->td_pflags & TDP_NORUNNINGBUF); + /* play bufdaemon */ + td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; + fl = buf_do_flush(vp); + td->td_pflags &= norunbuf; + mtx_lock(&nblock); + if (fl != 0) + continue; + if ((needsbuffer & flags) == 0) + break; + } + if (msleep(&needsbuffer, &nblock, + (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { + mtx_unlock(&nblock); + return (NULL); + } + } + mtx_unlock(&nblock); + } else { + /* + * We finally have a valid bp. We aren't quite out of the + * woods, we still have to reserve kva space. In order + * to keep fragmentation sane we only allocate kva in + * BKVASIZE chunks. + */ + maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; + + if (maxsize != bp->b_kvasize) { + vm_offset_t addr = 0; + int rv; + + bfreekva(bp); + + vm_map_lock(buffer_map); + if (vm_map_findspace(buffer_map, + vm_map_min(buffer_map), maxsize, &addr)) { + /* + * Buffer map is too fragmented. + * We must defragment the map. + */ + atomic_add_int(&bufdefragcnt, 1); + vm_map_unlock(buffer_map); + defrag = 1; + bp->b_flags |= B_INVAL; + brelse(bp); + goto restart; + } + rv = vm_map_insert(buffer_map, NULL, 0, addr, + addr + maxsize, VM_PROT_ALL, VM_PROT_ALL, + MAP_NOFAULT); + KASSERT(rv == KERN_SUCCESS, + ("vm_map_insert(buffer_map) rv %d", rv)); + vm_map_unlock(buffer_map); + bp->b_kvabase = (caddr_t)addr; + bp->b_kvasize = maxsize; + atomic_add_long(&bufspace, bp->b_kvasize); + atomic_add_int(&bufreusecnt, 1); + } + bp->b_saveaddr = bp->b_kvabase; + bp->b_data = bp->b_saveaddr; + } + return (bp); +} + +/* + * buf_daemon: + * + * buffer flushing daemon. Buffers are normally flushed by the + * update daemon but if it cannot keep up this process starts to + * take the load in an attempt to prevent getnewbuf() from blocking. + */ + +static struct kproc_desc buf_kp = { + "bufdaemon", + buf_daemon, + &bufdaemonproc +}; +SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); + +static int +buf_do_flush(struct vnode *vp) +{ + int flushed; + + flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); + if (flushed == 0) { + /* + * Could not find any buffers without rollback + * dependencies, so just write the first one + * in the hopes of eventually making progress. + */ + flushbufqueues(vp, QUEUE_DIRTY, 1); + } + return (flushed); +} + +static void +buf_daemon() +{ + int lodirtysave; + + /* + * This process needs to be suspended prior to shutdown sync. + */ + EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, + SHUTDOWN_PRI_LAST); + + /* + * This process is allowed to take the buffer cache to the limit + */ + curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; + mtx_lock(&bdlock); + for (;;) { + bd_request = 0; + mtx_unlock(&bdlock); + + kproc_suspend_check(bufdaemonproc); + lodirtysave = lodirtybuffers; + if (bd_speedupreq) { + lodirtybuffers = numdirtybuffers / 2; + bd_speedupreq = 0; + } + /* + * Do the flush. Limit the amount of in-transit I/O we + * allow to build up, otherwise we would completely saturate + * the I/O system. Wakeup any waiting processes before we + * normally would so they can run in parallel with our drain. + */ + while (numdirtybuffers > lodirtybuffers) { + if (buf_do_flush(NULL) == 0) + break; + kern_yield(PRI_UNCHANGED); + } + lodirtybuffers = lodirtysave; + + /* + * Only clear bd_request if we have reached our low water + * mark. The buf_daemon normally waits 1 second and + * then incrementally flushes any dirty buffers that have + * built up, within reason. + * + * If we were unable to hit our low water mark and couldn't + * find any flushable buffers, we sleep half a second. + * Otherwise we loop immediately. + */ + mtx_lock(&bdlock); + if (numdirtybuffers <= lodirtybuffers) { + /* + * We reached our low water mark, reset the + * request and sleep until we are needed again. + * The sleep is just so the suspend code works. + */ + bd_request = 0; + msleep(&bd_request, &bdlock, PVM, "psleep", hz); + } else { + /* + * We couldn't find any flushable dirty buffers but + * still have too many dirty buffers, we + * have to sleep and try again. (rare) + */ + msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); + } + } +} + +/* + * flushbufqueues: + * + * Try to flush a buffer in the dirty queue. We must be careful to + * free up B_INVAL buffers instead of write them, which NFS is + * particularly sensitive to. + */ +static int flushwithdeps = 0; +SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, + 0, "Number of buffers flushed with dependecies that require rollbacks"); + +static int +flushbufqueues(struct vnode *lvp, int queue, int flushdeps) +{ + struct buf *sentinel; + struct vnode *vp; + struct mount *mp; + struct buf *bp; + int hasdeps; + int flushed; + int target; + + if (lvp == NULL) { + target = numdirtybuffers - lodirtybuffers; + if (flushdeps && target > 2) + target /= 2; + } else + target = flushbufqtarget; + flushed = 0; + bp = NULL; + sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); + sentinel->b_qindex = QUEUE_SENTINEL; + mtx_lock(&bqlock); + TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); + while (flushed != target) { + bp = TAILQ_NEXT(sentinel, b_freelist); + if (bp != NULL) { + TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); + TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, + b_freelist); + } else + break; + /* + * Skip sentinels inserted by other invocations of the + * flushbufqueues(), taking care to not reorder them. + */ + if (bp->b_qindex == QUEUE_SENTINEL) + continue; + /* + * Only flush the buffers that belong to the + * vnode locked by the curthread. + */ + if (lvp != NULL && bp->b_vp != lvp) + continue; + if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) + continue; + if (bp->b_pin_count > 0) { + BUF_UNLOCK(bp); + continue; + } + BO_LOCK(bp->b_bufobj); + if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || + (bp->b_flags & B_DELWRI) == 0) { + BO_UNLOCK(bp->b_bufobj); + BUF_UNLOCK(bp); + continue; + } + BO_UNLOCK(bp->b_bufobj); + if (bp->b_flags & B_INVAL) { + bremfreel(bp); + mtx_unlock(&bqlock); + brelse(bp); + flushed++; + numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); + mtx_lock(&bqlock); + continue; + } + + if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { + if (flushdeps == 0) { + BUF_UNLOCK(bp); + continue; + } + hasdeps = 1; + } else + hasdeps = 0; + /* + * We must hold the lock on a vnode before writing + * one of its buffers. Otherwise we may confuse, or + * in the case of a snapshot vnode, deadlock the + * system. + * + * The lock order here is the reverse of the normal + * of vnode followed by buf lock. This is ok because + * the NOWAIT will prevent deadlock. + */ + vp = bp->b_vp; + if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { + BUF_UNLOCK(bp); + continue; + } + if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { + mtx_unlock(&bqlock); + CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", + bp, bp->b_vp, bp->b_flags); + if (curproc == bufdaemonproc) + vfs_bio_awrite(bp); + else { + bremfree(bp); + bwrite(bp); + notbufdflashes++; + } + vn_finished_write(mp); + VOP_UNLOCK(vp, 0); + flushwithdeps += hasdeps; + flushed++; + + /* + * Sleeping on runningbufspace while holding + * vnode lock leads to deadlock. + */ + if (curproc == bufdaemonproc) + waitrunningbufspace(); + numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); + mtx_lock(&bqlock); + continue; + } + vn_finished_write(mp); + BUF_UNLOCK(bp); + } + TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); + mtx_unlock(&bqlock); + free(sentinel, M_TEMP); + return (flushed); +} + +/* + * Check to see if a block is currently memory resident. + */ +struct buf * +incore(struct bufobj *bo, daddr_t blkno) +{ + struct buf *bp; + + BO_LOCK(bo); + bp = gbincore(bo, blkno); + BO_UNLOCK(bo); + return (bp); +} + +/* + * Returns true if no I/O is needed to access the + * associated VM object. This is like incore except + * it also hunts around in the VM system for the data. + */ + +static int +inmem(struct vnode * vp, daddr_t blkno) +{ + vm_object_t obj; + vm_offset_t toff, tinc, size; + vm_page_t m; + vm_ooffset_t off; + + ASSERT_VOP_LOCKED(vp, "inmem"); + + if (incore(&vp->v_bufobj, blkno)) + return 1; + if (vp->v_mount == NULL) + return 0; + obj = vp->v_object; + if (obj == NULL) + return (0); + + size = PAGE_SIZE; + if (size > vp->v_mount->mnt_stat.f_iosize) + size = vp->v_mount->mnt_stat.f_iosize; + off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; + + VM_OBJECT_LOCK(obj); + for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { + m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); + if (!m) + goto notinmem; + tinc = size; + if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) + tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); + if (vm_page_is_valid(m, + (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) + goto notinmem; + } + VM_OBJECT_UNLOCK(obj); + return 1; + +notinmem: + VM_OBJECT_UNLOCK(obj); + return (0); +} + +/* + * Set the dirty range for a buffer based on the status of the dirty + * bits in the pages comprising the buffer. The range is limited + * to the size of the buffer. + * + * Tell the VM system that the pages associated with this buffer + * are clean. This is used for delayed writes where the data is + * going to go to disk eventually without additional VM intevention. + * + * Note that while we only really need to clean through to b_bcount, we + * just go ahead and clean through to b_bufsize. + */ +static void +vfs_clean_pages_dirty_buf(struct buf *bp) +{ + vm_ooffset_t foff, noff, eoff; + vm_page_t m; + int i; + + if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) + return; + + foff = bp->b_offset; + KASSERT(bp->b_offset != NOOFFSET, + ("vfs_clean_pages_dirty_buf: no buffer offset")); + + VM_OBJECT_LOCK(bp->b_bufobj->bo_object); + vfs_drain_busy_pages(bp); + vfs_setdirty_locked_object(bp); + for (i = 0; i < bp->b_npages; i++) { + noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; + eoff = noff; + if (eoff > bp->b_offset + bp->b_bufsize) + eoff = bp->b_offset + bp->b_bufsize; + m = bp->b_pages[i]; + vfs_page_set_validclean(bp, foff, m); + /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ + foff = noff; + } + VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); +} + +static void +vfs_setdirty_locked_object(struct buf *bp) +{ + vm_object_t object; + int i; + + object = bp->b_bufobj->bo_object; + VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); + + /* + * We qualify the scan for modified pages on whether the + * object has been flushed yet. + */ + if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { + vm_offset_t boffset; + vm_offset_t eoffset; + + /* + * test the pages to see if they have been modified directly + * by users through the VM system. + */ + for (i = 0; i < bp->b_npages; i++) + vm_page_test_dirty(bp->b_pages[i]); + + /* + * Calculate the encompassing dirty range, boffset and eoffset, + * (eoffset - boffset) bytes. + */ + + for (i = 0; i < bp->b_npages; i++) { + if (bp->b_pages[i]->dirty) + break; + } + boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); + + for (i = bp->b_npages - 1; i >= 0; --i) { + if (bp->b_pages[i]->dirty) { + break; + } + } + eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); + + /* + * Fit it to the buffer. + */ + + if (eoffset > bp->b_bcount) + eoffset = bp->b_bcount; + + /* + * If we have a good dirty range, merge with the existing + * dirty range. + */ + + if (boffset < eoffset) { + if (bp->b_dirtyoff > boffset) + bp->b_dirtyoff = boffset; + if (bp->b_dirtyend < eoffset) + bp->b_dirtyend = eoffset; + } + } +} + +/* + * getblk: + * + * Get a block given a specified block and offset into a file/device. + * The buffers B_DONE bit will be cleared on return, making it almost + * ready for an I/O initiation. B_INVAL may or may not be set on + * return. The caller should clear B_INVAL prior to initiating a + * READ. + * + * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for + * an existing buffer. + * + * For a VMIO buffer, B_CACHE is modified according to the backing VM. + * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set + * and then cleared based on the backing VM. If the previous buffer is + * non-0-sized but invalid, B_CACHE will be cleared. + * + * If getblk() must create a new buffer, the new buffer is returned with + * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which + * case it is returned with B_INVAL clear and B_CACHE set based on the + * backing VM. + * + * getblk() also forces a bwrite() for any B_DELWRI buffer whos + * B_CACHE bit is clear. + * + * What this means, basically, is that the caller should use B_CACHE to + * determine whether the buffer is fully valid or not and should clear + * B_INVAL prior to issuing a read. If the caller intends to validate + * the buffer by loading its data area with something, the caller needs + * to clear B_INVAL. If the caller does this without issuing an I/O, + * the caller should set B_CACHE ( as an optimization ), else the caller + * should issue the I/O and biodone() will set B_CACHE if the I/O was + * a write attempt or if it was a successfull read. If the caller + * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR + * prior to issuing the READ. biodone() will *not* clear B_INVAL. + */ +struct buf * +getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, + int flags) +{ + struct buf *bp; + struct bufobj *bo; + int error; + + CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); + ASSERT_VOP_LOCKED(vp, "getblk"); + if (size > MAXBSIZE) + panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); + + bo = &vp->v_bufobj; +loop: + /* + * Block if we are low on buffers. Certain processes are allowed + * to completely exhaust the buffer cache. + * + * If this check ever becomes a bottleneck it may be better to + * move it into the else, when gbincore() fails. At the moment + * it isn't a problem. + */ + if (numfreebuffers == 0) { + if (TD_IS_IDLETHREAD(curthread)) + return NULL; + mtx_lock(&nblock); + needsbuffer |= VFS_BIO_NEED_ANY; + mtx_unlock(&nblock); + } + + BO_LOCK(bo); + bp = gbincore(bo, blkno); + if (bp != NULL) { + int lockflags; + /* + * Buffer is in-core. If the buffer is not busy nor managed, + * it must be on a queue. + */ + lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; + + if (flags & GB_LOCK_NOWAIT) + lockflags |= LK_NOWAIT; + + error = BUF_TIMELOCK(bp, lockflags, + BO_MTX(bo), "getblk", slpflag, slptimeo); + + /* + * If we slept and got the lock we have to restart in case + * the buffer changed identities. + */ + if (error == ENOLCK) + goto loop; + /* We timed out or were interrupted. */ + else if (error) + return (NULL); + + /* + * The buffer is locked. B_CACHE is cleared if the buffer is + * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set + * and for a VMIO buffer B_CACHE is adjusted according to the + * backing VM cache. + */ + if (bp->b_flags & B_INVAL) + bp->b_flags &= ~B_CACHE; + else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) + bp->b_flags |= B_CACHE; + if (bp->b_flags & B_MANAGED) + MPASS(bp->b_qindex == QUEUE_NONE); + else { + BO_LOCK(bo); + bremfree(bp); + BO_UNLOCK(bo); + } + + /* + * check for size inconsistancies for non-VMIO case. + */ + + if (bp->b_bcount != size) { + if ((bp->b_flags & B_VMIO) == 0 || + (size > bp->b_kvasize)) { + if (bp->b_flags & B_DELWRI) { + /* + * If buffer is pinned and caller does + * not want sleep waiting for it to be + * unpinned, bail out + * */ + if (bp->b_pin_count > 0) { + if (flags & GB_LOCK_NOWAIT) { + bqrelse(bp); + return (NULL); + } else { + bunpin_wait(bp); + } + } + bp->b_flags |= B_NOCACHE; + bwrite(bp); + } else { + if (LIST_EMPTY(&bp->b_dep)) { + bp->b_flags |= B_RELBUF; + brelse(bp); + } else { + bp->b_flags |= B_NOCACHE; + bwrite(bp); + } + } + goto loop; + } + } + + /* + * If the size is inconsistant in the VMIO case, we can resize + * the buffer. This might lead to B_CACHE getting set or + * cleared. If the size has not changed, B_CACHE remains + * unchanged from its previous state. + */ + + if (bp->b_bcount != size) + allocbuf(bp, size); + + KASSERT(bp->b_offset != NOOFFSET, + ("getblk: no buffer offset")); + + /* + * A buffer with B_DELWRI set and B_CACHE clear must + * be committed before we can return the buffer in + * order to prevent the caller from issuing a read + * ( due to B_CACHE not being set ) and overwriting + * it. + * + * Most callers, including NFS and FFS, need this to + * operate properly either because they assume they + * can issue a read if B_CACHE is not set, or because + * ( for example ) an uncached B_DELWRI might loop due + * to softupdates re-dirtying the buffer. In the latter + * case, B_CACHE is set after the first write completes, + * preventing further loops. + * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE + * above while extending the buffer, we cannot allow the + * buffer to remain with B_CACHE set after the write + * completes or it will represent a corrupt state. To + * deal with this we set B_NOCACHE to scrap the buffer + * after the write. + * + * We might be able to do something fancy, like setting + * B_CACHE in bwrite() except if B_DELWRI is already set, + * so the below call doesn't set B_CACHE, but that gets real + * confusing. This is much easier. + */ + + if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { + bp->b_flags |= B_NOCACHE; + bwrite(bp); + goto loop; + } + bp->b_flags &= ~B_DONE; + } else { + int bsize, maxsize, vmio; + off_t offset; + + /* + * Buffer is not in-core, create new buffer. The buffer + * returned by getnewbuf() is locked. Note that the returned + * buffer is also considered valid (not marked B_INVAL). + */ + BO_UNLOCK(bo); + /* + * If the user does not want us to create the buffer, bail out + * here. + */ + if (flags & GB_NOCREAT) + return NULL; + bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; + offset = blkno * bsize; + vmio = vp->v_object != NULL; + maxsize = vmio ? size + (offset & PAGE_MASK) : size; + maxsize = imax(maxsize, bsize); + + bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); + if (bp == NULL) { + if (slpflag || slptimeo) + return NULL; + goto loop; + } + + /* + * This code is used to make sure that a buffer is not + * created while the getnewbuf routine is blocked. + * This can be a problem whether the vnode is locked or not. + * If the buffer is created out from under us, we have to + * throw away the one we just created. + * + * Note: this must occur before we associate the buffer + * with the vp especially considering limitations in + * the splay tree implementation when dealing with duplicate + * lblkno's. + */ + BO_LOCK(bo); + if (gbincore(bo, blkno)) { + BO_UNLOCK(bo); + bp->b_flags |= B_INVAL; + brelse(bp); + goto loop; + } + + /* + * Insert the buffer into the hash, so that it can + * be found by incore. + */ + bp->b_blkno = bp->b_lblkno = blkno; + bp->b_offset = offset; + bgetvp(vp, bp); + BO_UNLOCK(bo); + + /* + * set B_VMIO bit. allocbuf() the buffer bigger. Since the + * buffer size starts out as 0, B_CACHE will be set by + * allocbuf() for the VMIO case prior to it testing the + * backing store for validity. + */ + + if (vmio) { + bp->b_flags |= B_VMIO; + KASSERT(vp->v_object == bp->b_bufobj->bo_object, + ("ARGH! different b_bufobj->bo_object %p %p %p\n", + bp, vp->v_object, bp->b_bufobj->bo_object)); + } else { + bp->b_flags &= ~B_VMIO; + KASSERT(bp->b_bufobj->bo_object == NULL, + ("ARGH! has b_bufobj->bo_object %p %p\n", + bp, bp->b_bufobj->bo_object)); + } + + allocbuf(bp, size); + bp->b_flags &= ~B_DONE; + } + CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); + BUF_ASSERT_HELD(bp); + KASSERT(bp->b_bufobj == bo, + ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); + return (bp); +} + +/* + * Get an empty, disassociated buffer of given size. The buffer is initially + * set to B_INVAL. + */ +struct buf * +geteblk(int size, int flags) +{ + struct buf *bp; + int maxsize; + + maxsize = (size + BKVAMASK) & ~BKVAMASK; + while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { + if ((flags & GB_NOWAIT_BD) && + (curthread->td_pflags & TDP_BUFNEED) != 0) + return (NULL); + } + allocbuf(bp, size); + bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ + BUF_ASSERT_HELD(bp); + return (bp); +} + + +/* + * This code constitutes the buffer memory from either anonymous system + * memory (in the case of non-VMIO operations) or from an associated + * VM object (in the case of VMIO operations). This code is able to + * resize a buffer up or down. + * + * Note that this code is tricky, and has many complications to resolve + * deadlock or inconsistant data situations. Tread lightly!!! + * There are B_CACHE and B_DELWRI interactions that must be dealt with by + * the caller. Calling this code willy nilly can result in the loss of data. + * + * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with + * B_CACHE for the non-VMIO case. + */ + +int +allocbuf(struct buf *bp, int size) +{ + int newbsize, mbsize; + int i; + + BUF_ASSERT_HELD(bp); + + if (bp->b_kvasize < size) + panic("allocbuf: buffer too small"); + + if ((bp->b_flags & B_VMIO) == 0) { + caddr_t origbuf; + int origbufsize; + /* + * Just get anonymous memory from the kernel. Don't + * mess with B_CACHE. + */ + mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); + if (bp->b_flags & B_MALLOC) + newbsize = mbsize; + else + newbsize = round_page(size); + + if (newbsize < bp->b_bufsize) { + /* + * malloced buffers are not shrunk + */ + if (bp->b_flags & B_MALLOC) { + if (newbsize) { + bp->b_bcount = size; + } else { + free(bp->b_data, M_BIOBUF); + if (bp->b_bufsize) { + atomic_subtract_long( + &bufmallocspace, + bp->b_bufsize); + bufspacewakeup(); + bp->b_bufsize = 0; + } + bp->b_saveaddr = bp->b_kvabase; + bp->b_data = bp->b_saveaddr; + bp->b_bcount = 0; + bp->b_flags &= ~B_MALLOC; + } + return 1; + } + vm_hold_free_pages(bp, newbsize); + } else if (newbsize > bp->b_bufsize) { + /* + * We only use malloced memory on the first allocation. + * and revert to page-allocated memory when the buffer + * grows. + */ + /* + * There is a potential smp race here that could lead + * to bufmallocspace slightly passing the max. It + * is probably extremely rare and not worth worrying + * over. + */ + if ( (bufmallocspace < maxbufmallocspace) && + (bp->b_bufsize == 0) && + (mbsize <= PAGE_SIZE/2)) { + + bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); + bp->b_bufsize = mbsize; + bp->b_bcount = size; + bp->b_flags |= B_MALLOC; + atomic_add_long(&bufmallocspace, mbsize); + return 1; + } + origbuf = NULL; + origbufsize = 0; + /* + * If the buffer is growing on its other-than-first allocation, + * then we revert to the page-allocation scheme. + */ + if (bp->b_flags & B_MALLOC) { + origbuf = bp->b_data; + origbufsize = bp->b_bufsize; + bp->b_data = bp->b_kvabase; + if (bp->b_bufsize) { + atomic_subtract_long(&bufmallocspace, + bp->b_bufsize); + bufspacewakeup(); + bp->b_bufsize = 0; + } + bp->b_flags &= ~B_MALLOC; + newbsize = round_page(newbsize); + } + vm_hold_load_pages( + bp, + (vm_offset_t) bp->b_data + bp->b_bufsize, + (vm_offset_t) bp->b_data + newbsize); + if (origbuf) { + bcopy(origbuf, bp->b_data, origbufsize); + free(origbuf, M_BIOBUF); + } + } + } else { + int desiredpages; + + newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); + desiredpages = (size == 0) ? 0 : + num_pages((bp->b_offset & PAGE_MASK) + newbsize); + + if (bp->b_flags & B_MALLOC) + panic("allocbuf: VMIO buffer can't be malloced"); + /* + * Set B_CACHE initially if buffer is 0 length or will become + * 0-length. + */ + if (size == 0 || bp->b_bufsize == 0) + bp->b_flags |= B_CACHE; + + if (newbsize < bp->b_bufsize) { + /* + * DEV_BSIZE aligned new buffer size is less then the + * DEV_BSIZE aligned existing buffer size. Figure out + * if we have to remove any pages. + */ + if (desiredpages < bp->b_npages) { + vm_page_t m; + + pmap_qremove((vm_offset_t)trunc_page( + (vm_offset_t)bp->b_data) + + (desiredpages << PAGE_SHIFT), + (bp->b_npages - desiredpages)); + VM_OBJECT_LOCK(bp->b_bufobj->bo_object); + for (i = desiredpages; i < bp->b_npages; i++) { + /* + * the page is not freed here -- it + * is the responsibility of + * vnode_pager_setsize + */ + m = bp->b_pages[i]; + KASSERT(m != bogus_page, + ("allocbuf: bogus page found")); + while (vm_page_sleep_if_busy(m, TRUE, + "biodep")) + continue; + + bp->b_pages[i] = NULL; + vm_page_lock(m); + vm_page_unwire(m, 0); + vm_page_unlock(m); + } + VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); + bp->b_npages = desiredpages; + } + } else if (size > bp->b_bcount) { + /* + * We are growing the buffer, possibly in a + * byte-granular fashion. + */ + vm_object_t obj; + vm_offset_t toff; + vm_offset_t tinc; + + /* + * Step 1, bring in the VM pages from the object, + * allocating them if necessary. We must clear + * B_CACHE if these pages are not valid for the + * range covered by the buffer. + */ + + obj = bp->b_bufobj->bo_object; + + VM_OBJECT_LOCK(obj); + while (bp->b_npages < desiredpages) { + vm_page_t m; + + /* + * We must allocate system pages since blocking + * here could interfere with paging I/O, no + * matter which process we are. + * + * We can only test VPO_BUSY here. Blocking on + * m->busy might lead to a deadlock: + * vm_fault->getpages->cluster_read->allocbuf + * Thus, we specify VM_ALLOC_IGN_SBUSY. + */ + m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + + bp->b_npages, VM_ALLOC_NOBUSY | + VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | + VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | + VM_ALLOC_COUNT(desiredpages - bp->b_npages)); + if (m->valid == 0) + bp->b_flags &= ~B_CACHE; + bp->b_pages[bp->b_npages] = m; + ++bp->b_npages; + } + + /* + * Step 2. We've loaded the pages into the buffer, + * we have to figure out if we can still have B_CACHE + * set. Note that B_CACHE is set according to the + * byte-granular range ( bcount and size ), new the + * aligned range ( newbsize ). + * + * The VM test is against m->valid, which is DEV_BSIZE + * aligned. Needless to say, the validity of the data + * needs to also be DEV_BSIZE aligned. Note that this + * fails with NFS if the server or some other client + * extends the file's EOF. If our buffer is resized, + * B_CACHE may remain set! XXX + */ + + toff = bp->b_bcount; + tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); + + while ((bp->b_flags & B_CACHE) && toff < size) { + vm_pindex_t pi; + + if (tinc > (size - toff)) + tinc = size - toff; + + pi = ((bp->b_offset & PAGE_MASK) + toff) >> + PAGE_SHIFT; + + vfs_buf_test_cache( + bp, + bp->b_offset, + toff, + tinc, + bp->b_pages[pi] + ); + toff += tinc; + tinc = PAGE_SIZE; + } + VM_OBJECT_UNLOCK(obj); + + /* + * Step 3, fixup the KVM pmap. Remember that + * bp->b_data is relative to bp->b_offset, but + * bp->b_offset may be offset into the first page. + */ + + bp->b_data = (caddr_t) + trunc_page((vm_offset_t)bp->b_data); + pmap_qenter( + (vm_offset_t)bp->b_data, + bp->b_pages, + bp->b_npages + ); + + bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | + (vm_offset_t)(bp->b_offset & PAGE_MASK)); + } + } + if (newbsize < bp->b_bufsize) + bufspacewakeup(); + bp->b_bufsize = newbsize; /* actual buffer allocation */ + bp->b_bcount = size; /* requested buffer size */ + return 1; +} + +void +biodone(struct bio *bp) +{ + struct mtx *mtxp; + void (*done)(struct bio *); + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + bp->bio_flags |= BIO_DONE; + done = bp->bio_done; + if (done == NULL) + wakeup(bp); + mtx_unlock(mtxp); + if (done != NULL) + done(bp); +} + +/* + * Wait for a BIO to finish. + * + * XXX: resort to a timeout for now. The optimal locking (if any) for this + * case is not yet clear. + */ +int +biowait(struct bio *bp, const char *wchan) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + while ((bp->bio_flags & BIO_DONE) == 0) + msleep(bp, mtxp, PRIBIO, wchan, hz / 10); + mtx_unlock(mtxp); + if (bp->bio_error != 0) + return (bp->bio_error); + if (!(bp->bio_flags & BIO_ERROR)) + return (0); + return (EIO); +} + +void +biofinish(struct bio *bp, struct devstat *stat, int error) +{ + + if (error) { + bp->bio_error = error; + bp->bio_flags |= BIO_ERROR; + } + if (stat != NULL) + devstat_end_transaction_bio(stat, bp); + biodone(bp); +} + +/* + * bufwait: + * + * Wait for buffer I/O completion, returning error status. The buffer + * is left locked and B_DONE on return. B_EINTR is converted into an EINTR + * error and cleared. + */ +int +bufwait(struct buf *bp) +{ + if (bp->b_iocmd == BIO_READ) + bwait(bp, PRIBIO, "biord"); + else + bwait(bp, PRIBIO, "biowr"); + if (bp->b_flags & B_EINTR) { + bp->b_flags &= ~B_EINTR; + return (EINTR); + } + if (bp->b_ioflags & BIO_ERROR) { + return (bp->b_error ? bp->b_error : EIO); + } else { + return (0); + } +} + + /* + * Call back function from struct bio back up to struct buf. + */ +static void +bufdonebio(struct bio *bip) +{ + struct buf *bp; + + bp = bip->bio_caller2; + bp->b_resid = bp->b_bcount - bip->bio_completed; + bp->b_resid = bip->bio_resid; /* XXX: remove */ + bp->b_ioflags = bip->bio_flags; + bp->b_error = bip->bio_error; + if (bp->b_error) + bp->b_ioflags |= BIO_ERROR; + bufdone(bp); + g_destroy_bio(bip); +} + +void +dev_strategy(struct cdev *dev, struct buf *bp) +{ + struct cdevsw *csw; + struct bio *bip; + int ref; + + if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) + panic("b_iocmd botch"); + for (;;) { + bip = g_new_bio(); + if (bip != NULL) + break; + /* Try again later */ + tsleep(&bp, PRIBIO, "dev_strat", hz/10); + } + bip->bio_cmd = bp->b_iocmd; + bip->bio_offset = bp->b_iooffset; + bip->bio_length = bp->b_bcount; + bip->bio_bcount = bp->b_bcount; /* XXX: remove */ + bip->bio_data = bp->b_data; + bip->bio_done = bufdonebio; + bip->bio_caller2 = bp; + bip->bio_dev = dev; + KASSERT(dev->si_refcount > 0, + ("dev_strategy on un-referenced struct cdev *(%s)", + devtoname(dev))); + csw = dev_refthread(dev, &ref); + if (csw == NULL) { + g_destroy_bio(bip); + bp->b_error = ENXIO; + bp->b_ioflags = BIO_ERROR; + bufdone(bp); + return; + } + (*csw->d_strategy)(bip); + dev_relthread(dev, ref); +} + +/* + * bufdone: + * + * Finish I/O on a buffer, optionally calling a completion function. + * This is usually called from an interrupt so process blocking is + * not allowed. + * + * biodone is also responsible for setting B_CACHE in a B_VMIO bp. + * In a non-VMIO bp, B_CACHE will be set on the next getblk() + * assuming B_INVAL is clear. + * + * For the VMIO case, we set B_CACHE if the op was a read and no + * read error occured, or if the op was a write. B_CACHE is never + * set if the buffer is invalid or otherwise uncacheable. + * + * biodone does not mess with B_INVAL, allowing the I/O routine or the + * initiator to leave B_INVAL set to brelse the buffer out of existance + * in the biodone routine. + */ +void +bufdone(struct buf *bp) +{ + struct bufobj *dropobj; + void (*biodone)(struct buf *); + + CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); + dropobj = NULL; + + KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); + BUF_ASSERT_HELD(bp); + + runningbufwakeup(bp); + if (bp->b_iocmd == BIO_WRITE) + dropobj = bp->b_bufobj; + /* call optional completion function if requested */ + if (bp->b_iodone != NULL) { + biodone = bp->b_iodone; + bp->b_iodone = NULL; + (*biodone) (bp); + if (dropobj) + bufobj_wdrop(dropobj); + return; + } + + bufdone_finish(bp); + + if (dropobj) + bufobj_wdrop(dropobj); +} + +void +bufdone_finish(struct buf *bp) +{ + BUF_ASSERT_HELD(bp); + + if (!LIST_EMPTY(&bp->b_dep)) + buf_complete(bp); + + if (bp->b_flags & B_VMIO) { + vm_ooffset_t foff; + vm_page_t m; + vm_object_t obj; + struct vnode *vp; + int bogus, i, iosize; + + obj = bp->b_bufobj->bo_object; + KASSERT(obj->paging_in_progress >= bp->b_npages, + ("biodone_finish: paging in progress(%d) < b_npages(%d)", + obj->paging_in_progress, bp->b_npages)); + + vp = bp->b_vp; + KASSERT(vp->v_holdcnt > 0, + ("biodone_finish: vnode %p has zero hold count", vp)); + KASSERT(vp->v_object != NULL, + ("biodone_finish: vnode %p has no vm_object", vp)); + + foff = bp->b_offset; + KASSERT(bp->b_offset != NOOFFSET, + ("biodone_finish: bp %p has no buffer offset", bp)); + + /* + * Set B_CACHE if the op was a normal read and no error + * occured. B_CACHE is set for writes in the b*write() + * routines. + */ + iosize = bp->b_bcount - bp->b_resid; + if (bp->b_iocmd == BIO_READ && + !(bp->b_flags & (B_INVAL|B_NOCACHE)) && + !(bp->b_ioflags & BIO_ERROR)) { + bp->b_flags |= B_CACHE; + } + bogus = 0; + VM_OBJECT_LOCK(obj); + for (i = 0; i < bp->b_npages; i++) { + int bogusflag = 0; + int resid; + + resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; + if (resid > iosize) + resid = iosize; + + /* + * cleanup bogus pages, restoring the originals + */ + m = bp->b_pages[i]; + if (m == bogus_page) { + bogus = bogusflag = 1; + m = vm_page_lookup(obj, OFF_TO_IDX(foff)); + if (m == NULL) + panic("biodone: page disappeared!"); + bp->b_pages[i] = m; + } + KASSERT(OFF_TO_IDX(foff) == m->pindex, + ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", + (intmax_t)foff, (uintmax_t)m->pindex)); + + /* + * In the write case, the valid and clean bits are + * already changed correctly ( see bdwrite() ), so we + * only need to do this here in the read case. + */ + if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { + KASSERT((m->dirty & vm_page_bits(foff & + PAGE_MASK, resid)) == 0, ("bufdone_finish:" + " page %p has unexpected dirty bits", m)); + vfs_page_set_valid(bp, foff, m); + } + + vm_page_io_finish(m); + vm_object_pip_subtract(obj, 1); + foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; + iosize -= resid; + } + vm_object_pip_wakeupn(obj, 0); + VM_OBJECT_UNLOCK(obj); + if (bogus) + pmap_qenter(trunc_page((vm_offset_t)bp->b_data), + bp->b_pages, bp->b_npages); + } + + /* + * For asynchronous completions, release the buffer now. The brelse + * will do a wakeup there if necessary - so no need to do a wakeup + * here in the async case. The sync case always needs to do a wakeup. + */ + + if (bp->b_flags & B_ASYNC) { + if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) + brelse(bp); + else + bqrelse(bp); + } else + bdone(bp); +} + +/* + * This routine is called in lieu of iodone in the case of + * incomplete I/O. This keeps the busy status for pages + * consistant. + */ +void +vfs_unbusy_pages(struct buf *bp) +{ + int i; + vm_object_t obj; + vm_page_t m; + + runningbufwakeup(bp); + if (!(bp->b_flags & B_VMIO)) + return; + + obj = bp->b_bufobj->bo_object; + VM_OBJECT_LOCK(obj); + for (i = 0; i < bp->b_npages; i++) { + m = bp->b_pages[i]; + if (m == bogus_page) { + m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); + if (!m) + panic("vfs_unbusy_pages: page missing\n"); + bp->b_pages[i] = m; + pmap_qenter(trunc_page((vm_offset_t)bp->b_data), + bp->b_pages, bp->b_npages); + } + vm_object_pip_subtract(obj, 1); + vm_page_io_finish(m); + } + vm_object_pip_wakeupn(obj, 0); + VM_OBJECT_UNLOCK(obj); +} + +/* + * vfs_page_set_valid: + * + * Set the valid bits in a page based on the supplied offset. The + * range is restricted to the buffer's size. + * + * This routine is typically called after a read completes. + */ +static void +vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) +{ + vm_ooffset_t eoff; + + /* + * Compute the end offset, eoff, such that [off, eoff) does not span a + * page boundary and eoff is not greater than the end of the buffer. + * The end of the buffer, in this case, is our file EOF, not the + * allocation size of the buffer. + */ + eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; + if (eoff > bp->b_offset + bp->b_bcount) + eoff = bp->b_offset + bp->b_bcount; + + /* + * Set valid range. This is typically the entire buffer and thus the + * entire page. + */ + if (eoff > off) + vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); +} + +/* + * vfs_page_set_validclean: + * + * Set the valid bits and clear the dirty bits in a page based on the + * supplied offset. The range is restricted to the buffer's size. + */ +static void +vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) +{ + vm_ooffset_t soff, eoff; + + /* + * Start and end offsets in buffer. eoff - soff may not cross a + * page boundry or cross the end of the buffer. The end of the + * buffer, in this case, is our file EOF, not the allocation size + * of the buffer. + */ + soff = off; + eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; + if (eoff > bp->b_offset + bp->b_bcount) + eoff = bp->b_offset + bp->b_bcount; + + /* + * Set valid range. This is typically the entire buffer and thus the + * entire page. + */ + if (eoff > soff) { + vm_page_set_validclean( + m, + (vm_offset_t) (soff & PAGE_MASK), + (vm_offset_t) (eoff - soff) + ); + } +} + +/* + * Ensure that all buffer pages are not busied by VPO_BUSY flag. If + * any page is busy, drain the flag. + */ +static void +vfs_drain_busy_pages(struct buf *bp) +{ + vm_page_t m; + int i, last_busied; + + VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); + last_busied = 0; + for (i = 0; i < bp->b_npages; i++) { + m = bp->b_pages[i]; + if ((m->oflags & VPO_BUSY) != 0) { + for (; last_busied < i; last_busied++) + vm_page_busy(bp->b_pages[last_busied]); + while ((m->oflags & VPO_BUSY) != 0) + vm_page_sleep(m, "vbpage"); + } + } + for (i = 0; i < last_busied; i++) + vm_page_wakeup(bp->b_pages[i]); +} + +/* + * This routine is called before a device strategy routine. + * It is used to tell the VM system that paging I/O is in + * progress, and treat the pages associated with the buffer + * almost as being VPO_BUSY. Also the object paging_in_progress + * flag is handled to make sure that the object doesn't become + * inconsistant. + * + * Since I/O has not been initiated yet, certain buffer flags + * such as BIO_ERROR or B_INVAL may be in an inconsistant state + * and should be ignored. + */ +void +vfs_busy_pages(struct buf *bp, int clear_modify) +{ + int i, bogus; + vm_object_t obj; + vm_ooffset_t foff; + vm_page_t m; + + if (!(bp->b_flags & B_VMIO)) + return; + + obj = bp->b_bufobj->bo_object; + foff = bp->b_offset; + KASSERT(bp->b_offset != NOOFFSET, + ("vfs_busy_pages: no buffer offset")); + VM_OBJECT_LOCK(obj); + vfs_drain_busy_pages(bp); + if (bp->b_bufsize != 0) + vfs_setdirty_locked_object(bp); + bogus = 0; + for (i = 0; i < bp->b_npages; i++) { + m = bp->b_pages[i]; + + if ((bp->b_flags & B_CLUSTER) == 0) { + vm_object_pip_add(obj, 1); + vm_page_io_start(m); + } + /* + * When readying a buffer for a read ( i.e + * clear_modify == 0 ), it is important to do + * bogus_page replacement for valid pages in + * partially instantiated buffers. Partially + * instantiated buffers can, in turn, occur when + * reconstituting a buffer from its VM backing store + * base. We only have to do this if B_CACHE is + * clear ( which causes the I/O to occur in the + * first place ). The replacement prevents the read + * I/O from overwriting potentially dirty VM-backed + * pages. XXX bogus page replacement is, uh, bogus. + * It may not work properly with small-block devices. + * We need to find a better way. + */ + if (clear_modify) { + pmap_remove_write(m); + vfs_page_set_validclean(bp, foff, m); + } else if (m->valid == VM_PAGE_BITS_ALL && + (bp->b_flags & B_CACHE) == 0) { + bp->b_pages[i] = bogus_page; + bogus++; + } + foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; + } + VM_OBJECT_UNLOCK(obj); + if (bogus) + pmap_qenter(trunc_page((vm_offset_t)bp->b_data), + bp->b_pages, bp->b_npages); +} + +/* + * vfs_bio_set_valid: + * + * Set the range within the buffer to valid. The range is + * relative to the beginning of the buffer, b_offset. Note that + * b_offset itself may be offset from the beginning of the first + * page. + */ +void +vfs_bio_set_valid(struct buf *bp, int base, int size) +{ + int i, n; + vm_page_t m; + + if (!(bp->b_flags & B_VMIO)) + return; + + /* + * Fixup base to be relative to beginning of first page. + * Set initial n to be the maximum number of bytes in the + * first page that can be validated. + */ + base += (bp->b_offset & PAGE_MASK); + n = PAGE_SIZE - (base & PAGE_MASK); + + VM_OBJECT_LOCK(bp->b_bufobj->bo_object); + for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { + m = bp->b_pages[i]; + if (n > size) + n = size; + vm_page_set_valid_range(m, base & PAGE_MASK, n); + base += n; + size -= n; + n = PAGE_SIZE; + } + VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); +} + +/* + * vfs_bio_clrbuf: + * + * If the specified buffer is a non-VMIO buffer, clear the entire + * buffer. If the specified buffer is a VMIO buffer, clear and + * validate only the previously invalid portions of the buffer. + * This routine essentially fakes an I/O, so we need to clear + * BIO_ERROR and B_INVAL. + * + * Note that while we only theoretically need to clear through b_bcount, + * we go ahead and clear through b_bufsize. + */ +void +vfs_bio_clrbuf(struct buf *bp) +{ + int i, j, mask; + caddr_t sa, ea; + + if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { + clrbuf(bp); + return; + } + bp->b_flags &= ~B_INVAL; + bp->b_ioflags &= ~BIO_ERROR; + VM_OBJECT_LOCK(bp->b_bufobj->bo_object); + if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && + (bp->b_offset & PAGE_MASK) == 0) { + if (bp->b_pages[0] == bogus_page) + goto unlock; + mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; + VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); + if ((bp->b_pages[0]->valid & mask) == mask) + goto unlock; + if ((bp->b_pages[0]->valid & mask) == 0) { + bzero(bp->b_data, bp->b_bufsize); + bp->b_pages[0]->valid |= mask; + goto unlock; + } + } + ea = sa = bp->b_data; + for(i = 0; i < bp->b_npages; i++, sa = ea) { + ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); + ea = (caddr_t)(vm_offset_t)ulmin( + (u_long)(vm_offset_t)ea, + (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); + if (bp->b_pages[i] == bogus_page) + continue; + j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; + mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; + VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); + if ((bp->b_pages[i]->valid & mask) == mask) + continue; + if ((bp->b_pages[i]->valid & mask) == 0) + bzero(sa, ea - sa); + else { + for (; sa < ea; sa += DEV_BSIZE, j++) { + if ((bp->b_pages[i]->valid & (1 << j)) == 0) + bzero(sa, DEV_BSIZE); + } + } + bp->b_pages[i]->valid |= mask; + } +unlock: + VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); + bp->b_resid = 0; +} + +/* + * vm_hold_load_pages and vm_hold_free_pages get pages into + * a buffers address space. The pages are anonymous and are + * not associated with a file object. + */ +static void +vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) +{ + vm_offset_t pg; + vm_page_t p; + int index; + + to = round_page(to); + from = round_page(from); + index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; + + for (pg = from; pg < to; pg += PAGE_SIZE, index++) { +tryagain: + /* + * note: must allocate system pages since blocking here + * could interfere with paging I/O, no matter which + * process we are. + */ + p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | + VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); + if (p == NULL) { + VM_WAIT; + goto tryagain; + } + pmap_qenter(pg, &p, 1); + bp->b_pages[index] = p; + } + bp->b_npages = index; +} + +/* Return pages associated with this buf to the vm system */ +static void +vm_hold_free_pages(struct buf *bp, int newbsize) +{ + vm_offset_t from; + vm_page_t p; + int index, newnpages; + + from = round_page((vm_offset_t)bp->b_data + newbsize); + newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; + if (bp->b_npages > newnpages) + pmap_qremove(from, bp->b_npages - newnpages); + for (index = newnpages; index < bp->b_npages; index++) { + p = bp->b_pages[index]; + bp->b_pages[index] = NULL; + if (p->busy != 0) + printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", + (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); + p->wire_count--; + vm_page_free(p); + atomic_subtract_int(&cnt.v_wire_count, 1); + } + bp->b_npages = newnpages; +} + +/* + * Map an IO request into kernel virtual address space. + * + * All requests are (re)mapped into kernel VA space. + * Notice that we use b_bufsize for the size of the buffer + * to be mapped. b_bcount might be modified by the driver. + * + * Note that even if the caller determines that the address space should + * be valid, a race or a smaller-file mapped into a larger space may + * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST + * check the return value. + */ +int +vmapbuf(struct buf *bp) +{ + caddr_t kva; + vm_prot_t prot; + int pidx; + + if (bp->b_bufsize < 0) + return (-1); + prot = VM_PROT_READ; + if (bp->b_iocmd == BIO_READ) + prot |= VM_PROT_WRITE; /* Less backwards than it looks */ + if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, + (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, + btoc(MAXPHYS))) < 0) + return (-1); + pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); + + kva = bp->b_saveaddr; + bp->b_npages = pidx; + bp->b_saveaddr = bp->b_data; + bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); + return(0); +} + +/* + * Free the io map PTEs associated with this IO operation. + * We also invalidate the TLB entries and restore the original b_addr. + */ +void +vunmapbuf(struct buf *bp) +{ + int npages; + + npages = bp->b_npages; + pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); + vm_page_unhold_pages(bp->b_pages, npages); + + bp->b_data = bp->b_saveaddr; +} + +void +bdone(struct buf *bp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + bp->b_flags |= B_DONE; + wakeup(bp); + mtx_unlock(mtxp); +} + +void +bwait(struct buf *bp, u_char pri, const char *wchan) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + while ((bp->b_flags & B_DONE) == 0) + msleep(bp, mtxp, pri, wchan, 0); + mtx_unlock(mtxp); +} + +int +bufsync(struct bufobj *bo, int waitfor) +{ + + return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); +} + +void +bufstrategy(struct bufobj *bo, struct buf *bp) +{ + int i = 0; + struct vnode *vp; + + vp = bp->b_vp; + KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); + KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, + ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); + i = VOP_STRATEGY(vp, bp); + KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); +} + +void +bufobj_wrefl(struct bufobj *bo) +{ + + KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); + ASSERT_BO_LOCKED(bo); + bo->bo_numoutput++; +} + +void +bufobj_wref(struct bufobj *bo) +{ + + KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); + BO_LOCK(bo); + bo->bo_numoutput++; + BO_UNLOCK(bo); +} + +void +bufobj_wdrop(struct bufobj *bo) +{ + + KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); + BO_LOCK(bo); + KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); + if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { + bo->bo_flag &= ~BO_WWAIT; + wakeup(&bo->bo_numoutput); + } + BO_UNLOCK(bo); +} + +int +bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) +{ + int error; + + KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); + ASSERT_BO_LOCKED(bo); + error = 0; + while (bo->bo_numoutput) { + bo->bo_flag |= BO_WWAIT; + error = msleep(&bo->bo_numoutput, BO_MTX(bo), + slpflag | (PRIBIO + 1), "bo_wwait", timeo); + if (error) + break; + } + return (error); +} + +void +bpin(struct buf *bp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + bp->b_pin_count++; + mtx_unlock(mtxp); +} + +void +bunpin(struct buf *bp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + if (--bp->b_pin_count == 0) + wakeup(bp); + mtx_unlock(mtxp); +} + +void +bunpin_wait(struct buf *bp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, bp); + mtx_lock(mtxp); + while (bp->b_pin_count > 0) + msleep(bp, mtxp, PRIBIO, "bwunpin", 0); + mtx_unlock(mtxp); +} + +#include "opt_ddb.h" +#ifdef DDB +#include <ddb/ddb.h> + +/* DDB command to show buffer data */ +DB_SHOW_COMMAND(buffer, db_show_buffer) +{ + /* get args */ + struct buf *bp = (struct buf *)addr; + + if (!have_addr) { + db_printf("usage: show buffer <addr>\n"); + return; + } + + db_printf("buf at %p\n", bp); + db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", + (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, + PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); + db_printf( + "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" + "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " + "b_dep = %p\n", + bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, + bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, + (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); + if (bp->b_npages) { + int i; + db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); + for (i = 0; i < bp->b_npages; i++) { + vm_page_t m; + m = bp->b_pages[i]; + db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, + (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); + if ((i + 1) < bp->b_npages) + db_printf(","); + } + db_printf("\n"); + } + db_printf(" "); + BUF_LOCKPRINTINFO(bp); +} + +DB_SHOW_COMMAND(lockedbufs, lockedbufs) +{ + struct buf *bp; + int i; + + for (i = 0; i < nbuf; i++) { + bp = &buf[i]; + if (BUF_ISLOCKED(bp)) { + db_show_buffer((uintptr_t)bp, 1, 0, NULL); + db_printf("\n"); + } + } +} + +DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) +{ + struct vnode *vp; + struct buf *bp; + + if (!have_addr) { + db_printf("usage: show vnodebufs <addr>\n"); + return; + } + vp = (struct vnode *)addr; + db_printf("Clean buffers:\n"); + TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { + db_show_buffer((uintptr_t)bp, 1, 0, NULL); + db_printf("\n"); + } + db_printf("Dirty buffers:\n"); + TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { + db_show_buffer((uintptr_t)bp, 1, 0, NULL); + db_printf("\n"); + } +} + +DB_COMMAND(countfreebufs, db_coundfreebufs) +{ + struct buf *bp; + int i, used = 0, nfree = 0; + + if (have_addr) { + db_printf("usage: countfreebufs\n"); + return; + } + + for (i = 0; i < nbuf; i++) { + bp = &buf[i]; + if ((bp->b_vflags & BV_INFREECNT) != 0) + nfree++; + else + used++; + } + + db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, + nfree + used); + db_printf("numfreebuffers is %d\n", numfreebuffers); +} +#endif /* DDB */ |
