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* Add a kqueue filter for writing to ufs filesystems which always returnsjlemon2001-06-051-0/+22
| | | | | | | true. This permits better interoperability with programs which register filters on their stdin/stdout handles. Submitted by: Niels Provos <provos@citi.umich.edu>
* There seems to be a problem that the order of disk write operation beingobrien2001-06-051-2/+11
| | | | | | | | | | | incorrect due to a missing check for some dependency. This change avoids the freelist corruption (but not the temporarily inconsistent state of the file system). A message is printed as a reminder of the under lying problem when a pagedep structure is not freed due to the NEWBLOCK flag being set. Submitted by: Tor.Egge@fast.no
* Revert the previous commit in favor of the fix in rev 1.42 ofjhb2001-05-301-1/+0
| | | | | | ufs/ffs/ffs_extern.h instead. Requested by: bde
* Forward declare struct cg to quiet a warning.jhb2001-05-301-0/+1
| | | | Submitted by: bde
* Include <ufs/ffs/fs.h> to get the definition of struct cg to quiet ajhb2001-05-291-0/+1
| | | | warning.
* Remove last vestiges of MFS.phk2001-05-292-14/+4
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* Remove MFS from the kernel.phk2001-05-294-944/+0
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* Add a check to determine whether extended attributes have beentmm2001-05-251-0/+8
| | | | | | | | | | initialized on the file system before trying to grab the lock of the per-mount extattr structure, as this lock is unitialized in that case. This is needed because ufs_extattr_vnode_inactive is called from ufs_inactive, which is also used by EA-unaware file systems such as ext2fs. Reviewed by: rwatson
* o Merge contents of struct pcred into struct ucred. Specifically, add therwatson2001-05-252-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | real uid, saved uid, real gid, and saved gid to ucred, as well as the pcred->pc_uidinfo, which was associated with the real uid, only rename it to cr_ruidinfo so as not to conflict with cr_uidinfo, which corresponds to the effective uid. o Remove p_cred from struct proc; add p_ucred to struct proc, replacing original macro that pointed. p->p_ucred to p->p_cred->pc_ucred. o Universally update code so that it makes use of ucred instead of pcred, p->p_ucred instead of p->p_pcred, cr_ruidinfo instead of p_uidinfo, cr_{r,sv}{u,g}id instead of p_*, etc. o Remove pcred0 and its initialization from init_main.c; initialize cr_ruidinfo there. o Restruction many credential modification chunks to always crdup while we figure out locking and optimizations; generally speaking, this means moving to a structure like this: newcred = crdup(oldcred); ... p->p_ucred = newcred; crfree(oldcred); It's not race-free, but better than nothing. There are also races in sys_process.c, all inter-process authorization, fork, exec, and exit. o Remove sigio->sio_ruid since sigio->sio_ucred now contains the ruid; remove comments indicating that the old arrangement was a problem. o Restructure exec1() a little to use newcred/oldcred arrangement, and use improved uid management primitives. o Clean up exit1() so as to do less work in credential cleanup due to pcred removal. o Clean up fork1() so as to do less work in credential cleanup and allocation. o Clean up ktrcanset() to take into account changes, and move to using suser_xxx() instead of performing a direct uid==0 comparision. o Improve commenting in various kern_prot.c credential modification calls to better document current behavior. In a couple of places, current behavior is a little questionable and we need to check POSIX.1 to make sure it's "right". More commenting work still remains to be done. o Update credential management calls, such as crfree(), to take into account new ruidinfo reference. o Modify or add the following uid and gid helper routines: change_euid() change_egid() change_ruid() change_rgid() change_svuid() change_svgid() In each case, the call now acts on a credential not a process, and as such no longer requires more complicated process locking/etc. They now assume the caller will do any necessary allocation of an exclusive credential reference. Each is commented to document its reference requirements. o CANSIGIO() is simplified to require only credentials, not processes and pcreds. o Remove lots of (p_pcred==NULL) checks. o Add an XXX to authorization code in nfs_lock.c, since it's questionable, and needs to be considered carefully. o Simplify posix4 authorization code to require only credentials, not processes and pcreds. Note that this authorization, as well as CANSIGIO(), needs to be updated to use the p_cansignal() and p_cansched() centralized authorization routines, as they currently do not take into account some desirable restrictions that are handled by the centralized routines, as well as being inconsistent with other similar authorization instances. o Update libkvm to take these changes into account. Obtained from: TrustedBSD Project Reviewed by: green, bde, jhb, freebsd-arch, freebsd-audit
* This patch implements O_DIRECT about 80% of the way. It takes a patchsetdillon2001-05-241-7/+29
| | | | | | | | | | | | | | | | Tor created a while ago, removes the raw I/O piece (that has cache coherency problems), and adds a buffer cache / VM freeing piece. Essentially this patch causes O_DIRECT I/O to not be left in the cache, but does not prevent it from going through the cache, hence the 80%. For the last 20% we need a method by which the I/O can be issued directly to buffer supplied by the user process and bypass the buffer cache entirely, but still maintain cache coherency. I also have the code working under -stable but the changes made to sys/file.h may not be MFCable, so an MFC is not on the table yet. Submitted by: tegge, dillon
* ufs_bmaparray() may block on IO, drop vm mutex and aquire Giant whenalfred2001-05-231-0/+10
| | | | calling it from the pager routine
* - FDESC, FIFO, NULL, PORTAL, PROC, UMAP and UNION fileru2001-05-231-1/+1
| | | | | | | | | | | | | | | systems were repo-copied from sys/miscfs to sys/fs. - Renamed the following file systems and their modules: fdesc -> fdescfs, portal -> portalfs, union -> unionfs. - Renamed corresponding kernel options: FDESC -> FDESCFS, PORTAL -> PORTALFS, UNION -> UNIONFS. - Install header files for the above file systems. - Removed bogus -I${.CURDIR}/../../sys CFLAGS from userland Makefiles.
* Update softdep_setup_directory_add prototype to reflect changes inmckusick2001-05-201-2/+3
| | | | | | actual function. Obtained from: Jim Bloom <bloom@jbloom.jbloom.org>
* Must ensure that all the entries on the pd_pendinghd list have beenmckusick2001-05-191-3/+11
| | | | | | | | | | | | | | committed to disk before clearing them. More specifically, when free_newdirblk is called, we know that the inode claims the new directory block. However, if the associated pagedep is still linked onto the directory buffer dependency chain, then some of the entries on the pd_pendinghd list may not be committed to disk yet. In this case, we will simply note that the inode claims the block and let the pd_pendinghd list be processed when the pagedep is next written. If the pagedep is no longer on the buffer dependency chain, then all the entries on the pd_pending list are committed to disk and we can free them in free_newdirblk. This corrects a window of vulnerability introduced in the code added in version 1.95.
* Introduce a global lock for the vm subsystem (vm_mtx).alfred2001-05-191-9/+38
| | | | | | | | | | | | | | | | | | | vm_mtx does not recurse and is required for most low level vm operations. faults can not be taken without holding Giant. Memory subsystems can now call the base page allocators safely. Almost all atomic ops were removed as they are covered under the vm mutex. Alpha and ia64 now need to catch up to i386's trap handlers. FFS and NFS have been tested, other filesystems will need minor changes (grabbing the vm lock when twiddling page properties). Reviewed (partially) by: jake, jhb
* Must be a bit less aggressive about freeing pagedep structures.mckusick2001-05-181-1/+1
| | | | | Obtained from: Robert Watson <rwatson@FreeBSD.org> and Matthew Jacob <mjacob@feral.com>
* When a new block is allocated to a directory, an fsync of a filemckusick2001-05-174-39/+242
| | | | | | | | | | | | | whose name is within that block must ensure not only that the block containing the file name has been written, but also that the on-disk directory inode references that block. When a new directory block is created, we allocate a newdirblk structure which is linked to the associated allocdirect (on its ad_newdirblk list). When the allocdirect has been satisfied, the newdirblk structure is moved to the inodedep id_bufwait list of its directory to await the inode being written. When the inode is written, the directory entries are fully committed and can be deleted from their pagedep->id_pendinghd and inodedep->id_pendinghd lists.
* Change the second argument of vflush() to an integer that specifiesiedowse2001-05-161-3/+3
| | | | | | | | | | | | | | | | | | | | the number of references on the filesystem root vnode to be both expected and released. Many filesystems hold an extra reference on the filesystem root vnode, which must be accounted for when determining if the filesystem is busy and then released if it isn't busy. The old `skipvp' approach required individual filesystem xxx_unmount functions to re-implement much of vflush()'s logic to deal with the root vnode. All 9 filesystems that hold an extra reference on the root vnode got the logic wrong in the case of forced unmounts, so `umount -f' would always fail if there were any extra root vnode references. Fix this issue centrally in vflush(), now that we can. This commit also fixes a vnode reference leak in devfs, which could result in idle devfs filesystems that refuse to unmount. Reviewed by: phk, bp
* Further fixes for deadlock in the presence of multiple snapshots.mckusick2001-05-141-7/+20
| | | | | There are still more to find, but this fix should cover the common cases that folks are hitting.
* If the effective link count is zero when an NFS file handle requestmckusick2001-05-131-1/+3
| | | | | | | | | | | | | | | | comes in for it, the file is really gone, so return ESTALE. The problem arises when the last reference to an FFS file is released because soft-updates may delay the actual freeing of the inode for some time. Since there are no filesystem links or open file descriptors referencing the inode, from the point of view of the system, the file is inaccessible. However, if the filesystem is NFS exported, then the remote client can still access the inode via ufs_fhtovp() until the inode really goes away. To prevent this anomoly, it is necessary to begin returning ESTALE at the same time that the file ceases to be accessible to the local filesystem. Obtained from: Ian Dowse <iedowse@maths.tcd.ie>
* Remove yet another deadlock case.mckusick2001-05-111-3/+6
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* When running with soft updates, track the number of blocks and filesmckusick2001-05-089-11/+119
| | | | | | | | | | | | | that are committed to being freed and reflect these blocks in the counts returned by statfs (and thus also by the `df' command). This change allows programs such as those that do news expiration to know when to stop if they are trying to create a certain percentage of free space. Note that this change does not solve the much harder problem of making this to-be-freed space available to applications that want it (thus on a nearly full filesystem, you may still encounter out-of-space conditions even though the free space will show up eventually). Hopefully this harder problem will be the subject of a future enhancement.
* Several fixes for units errors:mckusick2001-05-081-10/+19
| | | | | | | | | | | | | | | | | 1) Do not assume that the superblock will be of size fs->fs_bsize. This fixes a panic when taking a snapshot on a filesystem with a block size bigger than 8K. 2) Properly calculate the number of fragments that follow the superblock summary information. This fixes a bug with inconsistent snapshots. 3) When cleaning up a snapshot that is about to be removed, properly calculate the number of blocks that need to be checked. This fixes a bug that created partially allocated inodes. 4) When moving blocks from a snapshot that is about to be removed to another snapshot, properly account for the reduced number of blocks in the snapshot from which they are taken. This fixes a bug in which the number of blocks released from a snapshot did not match the number that it claimed to have.
* When syncing out snapshot metadata, we must temporarily allow recursivemckusick2001-05-081-27/+29
| | | | | buffer locking so as to avoid locking against ourselves if we need to write filesystem metadata.
* Refinement to revision 1.16 of ufs/ffs/ffs_snapshot.c to reducemckusick2001-05-043-120/+227
| | | | | the amount of time that the filesystem must be suspended. The current snapshot is elided as well as the earlier snapshots.
* Use ufs_bmaparray() rather than VOP_BMAP() on our own vnodes.phk2001-05-011-2/+2
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* Remove blatantly pointless call to VOP_BMAP().phk2001-05-012-9/+3
| | | | Use ufs_bmaparray() rather than VOP_BMAP() on our own vnodes.
* Implement vop_std{get|put}pages() and add them to the default vop[].phk2001-05-013-18/+0
| | | | | Un-copy&paste all the VOP_{GET|PUT}PAGES() functions which do nothing but the default.
* Undo part of the tangle of having sys/lock.h and sys/mutex.h included inmarkm2001-05-012-6/+11
| | | | | | | | | | | other "system" header files. Also help the deprecation of lockmgr.h by making it a sub-include of sys/lock.h and removing sys/lockmgr.h form kernel .c files. Sort sys/*.h includes where possible in affected files. OK'ed by: bde (with reservations)
* VOP_BALLOC was never really a VOP in the first place, so convert itphk2001-04-2911-49/+44
| | | | to UFS_BALLOC like the other "between UFS and FFS function interfaces".
* Add a vop_stdbmap(), and make it part of the default vop vector.phk2001-04-291-25/+1
| | | | | | Make 7 filesystems which don't really know about VOP_BMAP rely on the default vector, rather than more or less complete local vop_nopbmap() implementations.
* Call ufs_bmaparray() directly instead of indirectly via VOP_BMAP().phk2001-04-291-2/+3
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* Remove two unused arguments from ufs_bmaparray().phk2001-04-292-22/+17
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* Remove faint traces of blind copy&paste.phk2001-04-291-1/+0
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* Remove faint traces of non-existant ffs_bmap().phk2001-04-291-2/+0
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* Revert consequences of changes to mount.h, part 2.grog2001-04-2916-32/+0
| | | | Requested by: bde
* Rather than copying all the indirect blocks of the snapshot,mckusick2001-04-261-35/+19
| | | | | | simply mark them as BLK_NOCOPY. This trick cuts the initial size of the snapshot in half and cuts the time to take a snapshot by a third.
* When closing the last reference to an unlinked file, it is freedmckusick2001-04-253-26/+104
| | | | | | | | | | | | | | | by the inactive routine. Because the freeing causes the filesystem to be modified, the close must be held up during periods when the filesystem is suspended. For snapshots to be consistent across crashes, they must write blocks that they copy and claim those written blocks in their on-disk block pointers before the old blocks that they referenced can be allowed to be written. Close a loophole that allowed unwritten blocks to be skipped when doing ffs_sync with a request to wait for all I/O activity to be completed.
* Move the netexport structure from the fs-specific mountstructurephk2001-04-256-38/+6
| | | | | | | | | | | | | | to struct mount. This makes the "struct netexport *" paramter to the vfs_export and vfs_checkexport interface unneeded. Consequently that all non-stacking filesystems can use vfs_stdcheckexp(). At the same time, make it a pointer to a struct netexport in struct mount, so that we can remove the bogus AF_MAX and #include <net/radix.h> from <sys/mount.h>
* Pre-dirpref versions of fsck may zero out the new superblock fieldsiedowse2001-04-241-0/+6
| | | | | | | | | | | fs_contigdirs, fs_avgfilesize and fs_avgfpdir. This could cause panics if these fields were zeroed while a filesystem was mounted read-only, and then remounted read-write. Add code to ffs_reload() which copies the fs_contigdirs pointer from the previous superblock, and reinitialises fs_avgf* if necessary. Reviewed by: mckusick
* Correct #includes to work with fixed sys/mount.h.grog2001-04-2316-0/+32
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* This patch removes the VOP_BWRITE() vector.phk2001-04-171-1/+0
| | | | | | | | | | | | | VOP_BWRITE() was a hack which made it possible for NFS client side to use struct buf with non-bio backing. This patch takes a more general approach and adds a bp->b_op vector where more methods can be added. The success of this patch depends on bp->b_op being initialized all relevant places for some value of "relevant" which is not easy to determine. For now the buffers have grown a b_magic element which will make such issues a tiny bit easier to debug.
* Add debugging option to always read/write cylinder groups as fullmckusick2001-04-171-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sized blocks. To enable this option, use: `sysctl -w debug.bigcgs=1'. Add debugging option to disable background writes of cylinder groups. To enable this option, use: `sysctl -w debug.dobkgrdwrite=0'. These debugging options should be tried on systems that are panicing with corrupted cylinder group maps to see if it makes the problem go away. The set of panics in question are: ffs_clusteralloc: map mismatch ffs_nodealloccg: map corrupted ffs_nodealloccg: block not in map ffs_alloccg: map corrupted ffs_alloccg: block not in map ffs_alloccgblk: cyl groups corrupted ffs_alloccgblk: can't find blk in cyl ffs_checkblk: partially free fragment The following panics are less likely to be related to this problem, but might be helped by these debugging options: ffs_valloc: dup alloc ffs_blkfree: freeing free block ffs_blkfree: freeing free frag ffs_vfree: freeing free inode If you try these options, please report whether they helped reduce your bitmap corruption panics to Kirk McKusick at <mckusick@mckusick.com> and to Matt Dillon <dillon@earth.backplane.com>.
* Background fsck sysctl operations must use vn_start_write andmckusick2001-04-171-8/+14
| | | | | vn_finished_write so that they do not attempt to modify a suspended filesystem.
* In my first reading of POSIX.1e, I misinterpreted handling of therwatson2001-04-172-88/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ACL_USER_OBJ and ACL_GROUP_OBJ fields, believing that modification of the access ACL could be used by privileged processes to change file/directory ownership. In fact, this is incorrect; ACL_*_OBJ (+ ACL_MASK and ACL_OTHER) should have undefined ae_id fields; this commit attempts to correct that misunderstanding. o Modify arguments to vaccess_acl_posix1e() to accept the uid and gid associated with the vnode, as those can no longer be extracted from the ACL passed as an argument. Perform all comparisons against the passed arguments. This actually has the effect of simplifying a number of components of this call, as well as reducing the indent level, but now seperates handling of ACL_GROUP_OBJ from ACL_GROUP. o Modify acl_posix1e_check() to return EINVAL if the ae_id field of any of the ACL_{USER_OBJ,GROUP_OBJ,MASK,OTHER} entries is a value other than ACL_UNDEFINED_ID. As a temporary work-around to allow clean upgrades, set the ae_id field to ACL_UNDEFINED_ID before each check so that this cannot cause a failure in the short term (this work-around will be removed when the userland libraries and utilities are updated to take this change into account). o Modify ufs_sync_acl_from_inode() so that it forces ACL_{USER_OBJ,GROUP_OBJ,MASK,OTHER} ae_id fields to ACL_UNDEFINED_ID when synchronizing the ACL from the inode. o Modify ufs_sync_inode_from_acl to not propagate uid and gid information to the inode from the ACL during ACL update. Also modify the masking of permission bits that may be set from ALLPERMS to (S_IRWXU|S_IRWXG|S_IRWXO), as ACLs currently do not carry none-ACCESSPERMS (S_ISUID, S_ISGID, S_ISTXT). o Modify ufs_getacl() so that when it emulates an access ACL from the inode, it initializes the ae_id fields to ACL_UNDEFINED_ID. o Clean up ufs_setacl() substantially since it is no longer possible to perform chown/chgrp operations using vop_setacl(), so all the access control for that can be eliminated. o Modify ufs_access() so that it passes owner uid and gid information into vaccess_acl_posix1e(). Pointed out by: jedger Obtained from: TrustedBSD Project
* Update to describe use of mdconfig instead of deprecated vnconfig.mckusick2001-04-141-3/+3
| | | | Submitted by: Steve Ames <steve@virtual-voodoo.com>
* This checkin adds support in ufs/ffs for the FS_NEEDSFSCK flag.mckusick2001-04-143-8/+19
| | | | | | | | | | | | | | | | | | | It is described in ufs/ffs/fs.h as follows: /* * Filesystem flags. * * Note that the FS_NEEDSFSCK flag is set and cleared only by the * fsck utility. It is set when background fsck finds an unexpected * inconsistency which requires a traditional foreground fsck to be * run. Such inconsistencies should only be found after an uncorrectable * disk error. A foreground fsck will clear the FS_NEEDSFSCK flag when * it has successfully cleaned up the filesystem. The kernel uses this * flag to enforce that inconsistent filesystems be mounted read-only. */ #define FS_UNCLEAN 0x01 /* filesystem not clean at mount */ #define FS_DOSOFTDEP 0x02 /* filesystem using soft dependencies */ #define FS_NEEDSFSCK 0x04 /* filesystem needs sync fsck before mount */
* Directory layout preference improvements from Grigoriy Orlov <gluk@ptci.ru>.mckusick2001-04-103-21/+143
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | His description of the problem and solution follow. My own tests show speedups on typical filesystem intensive workloads of 5% to 12% which is very impressive considering the small amount of code change involved. ------ One day I noticed that some file operations run much faster on small file systems then on big ones. I've looked at the ffs algorithms, thought about them, and redesigned the dirpref algorithm. First I want to describe the results of my tests. These results are old and I have improved the algorithm after these tests were done. Nevertheless they show how big the perfomance speedup may be. I have done two file/directory intensive tests on a two OpenBSD systems with old and new dirpref algorithm. The first test is "tar -xzf ports.tar.gz", the second is "rm -rf ports". The ports.tar.gz file is the ports collection from the OpenBSD 2.8 release. It contains 6596 directories and 13868 files. The test systems are: 1. Celeron-450, 128Mb, two IDE drives, the system at wd0, file system for test is at wd1. Size of test file system is 8 Gb, number of cg=991, size of cg is 8m, block size = 8k, fragment size = 1k OpenBSD-current from Dec 2000 with BUFCACHEPERCENT=35 2. PIII-600, 128Mb, two IBM DTLA-307045 IDE drives at i815e, the system at wd0, file system for test is at wd1. Size of test file system is 40 Gb, number of cg=5324, size of cg is 8m, block size = 8k, fragment size = 1k OpenBSD-current from Dec 2000 with BUFCACHEPERCENT=50 You can get more info about the test systems and methods at: http://www.ptci.ru/gluk/dirpref/old/dirpref.html Test Results tar -xzf ports.tar.gz rm -rf ports mode old dirpref new dirpref speedup old dirprefnew dirpref speedup First system normal 667 472 1.41 477 331 1.44 async 285 144 1.98 130 14 9.29 sync 768 616 1.25 477 334 1.43 softdep 413 252 1.64 241 38 6.34 Second system normal 329 81 4.06 263.5 93.5 2.81 async 302 25.7 11.75 112 2.26 49.56 sync 281 57.0 4.93 263 90.5 2.9 softdep 341 40.6 8.4 284 4.76 59.66 "old dirpref" and "new dirpref" columns give a test time in seconds. speedup - speed increasement in times, ie. old dirpref / new dirpref. ------ Algorithm description The old dirpref algorithm is described in comments: /* * Find a cylinder to place a directory. * * The policy implemented by this algorithm is to select from * among those cylinder groups with above the average number of * free inodes, the one with the smallest number of directories. */ A new directory is allocated in a different cylinder groups than its parent directory resulting in a directory tree that is spreaded across all the cylinder groups. This spreading out results in a non-optimal access to the directories and files. When we have a small filesystem it is not a problem but when the filesystem is big then perfomance degradation becomes very apparent. What I mean by a big file system ? 1. A big filesystem is a filesystem which occupy 20-30 or more percent of total drive space, i.e. first and last cylinder are physically located relatively far from each other. 2. It has a relatively large number of cylinder groups, for example more cylinder groups than 50% of the buffers in the buffer cache. The first results in long access times, while the second results in many buffers being used by metadata operations. Such operations use cylinder group blocks and on-disk inode blocks. The cylinder group block (fs->fs_cblkno) contains struct cg, inode and block bit maps. It is 2k in size for the default filesystem parameters. If new and parent directories are located in different cylinder groups then the system performs more input/output operations and uses more buffers. On filesystems with many cylinder groups, lots of cache buffers are used for metadata operations. My solution for this problem is very simple. I allocate many directories in one cylinder group. I also do some things, so that the new allocation method does not cause excessive fragmentation and all directory inodes will not be located at a location far from its file's inodes and data. The algorithm is: /* * Find a cylinder group to place a directory. * * The policy implemented by this algorithm is to allocate a * directory inode in the same cylinder group as its parent * directory, but also to reserve space for its files inodes * and data. Restrict the number of directories which may be * allocated one after another in the same cylinder group * without intervening allocation of files. * * If we allocate a first level directory then force allocation * in another cylinder group. */ My early versions of dirpref give me a good results for a wide range of file operations and different filesystem capacities except one case: those applications that create their entire directory structure first and only later fill this structure with files. My solution for such and similar cases is to limit a number of directories which may be created one after another in the same cylinder group without intervening file creations. For this purpose, I allocate an array of counters at mount time. This array is linked to the superblock fs->fs_contigdirs[cg]. Each time a directory is created the counter increases and each time a file is created the counter decreases. A 60Gb filesystem with 8mb/cg requires 10kb of memory for the counters array. The maxcontigdirs is a maximum number of directories which may be created without an intervening file creation. I found in my tests that the best performance occurs when I restrict the number of directories in one cylinder group such that all its files may be located in the same cylinder group. There may be some deterioration in performance if all the file inodes are in the same cylinder group as its containing directory, but their data partially resides in a different cylinder group. The maxcontigdirs value is calculated to try to prevent this condition. Since there is no way to know how many files and directories will be allocated later I added two optimization parameters in superblock/tunefs. They are: int32_t fs_avgfilesize; /* expected average file size */ int32_t fs_avgfpdir; /* expected # of files per directory */ These parameters have reasonable defaults but may be tweeked for special uses of a filesystem. They are only necessary in rare cases like better tuning a filesystem being used to store a squid cache. I have been using this algorithm for about 3 months. I have done a lot of testing on filesystems with different capacities, average filesize, average number of files per directory, and so on. I think this algorithm has no negative impact on filesystem perfomance. It works better than the default one in all cases. The new dirpref will greatly improve untarring/removing/coping of big directories, decrease load on cvs servers and much more. The new dirpref doesn't speedup a compilation process, but also doesn't slow it down. Obtained from: Grigoriy Orlov <gluk@ptci.ru>
* o Indent sub-section headings to be consistent with README.extattr.rwatson2001-04-031-2/+2
| | | | Obtained from: TrustedBSD Project
* o Introduce a README file describing briefly how to use access controlrwatson2001-04-031-0/+51
| | | | | | lists, in the style of FFS README files for soft updates and snapshots. Obtained from: TrustedBSD Project
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