diff options
Diffstat (limited to 'fs/xfs/xfs_sync.c')
| -rw-r--r-- | fs/xfs/xfs_sync.c | 1065 |
1 files changed, 1065 insertions, 0 deletions
diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c new file mode 100644 index 0000000..4604f90 --- /dev/null +++ b/fs/xfs/xfs_sync.c @@ -0,0 +1,1065 @@ +/* + * Copyright (c) 2000-2005 Silicon Graphics, Inc. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_types.h" +#include "xfs_bit.h" +#include "xfs_log.h" +#include "xfs_inum.h" +#include "xfs_trans.h" +#include "xfs_trans_priv.h" +#include "xfs_sb.h" +#include "xfs_ag.h" +#include "xfs_mount.h" +#include "xfs_bmap_btree.h" +#include "xfs_inode.h" +#include "xfs_dinode.h" +#include "xfs_error.h" +#include "xfs_filestream.h" +#include "xfs_vnodeops.h" +#include "xfs_inode_item.h" +#include "xfs_quota.h" +#include "xfs_trace.h" +#include "xfs_fsops.h" + +#include <linux/kthread.h> +#include <linux/freezer.h> + +struct workqueue_struct *xfs_syncd_wq; /* sync workqueue */ + +/* + * The inode lookup is done in batches to keep the amount of lock traffic and + * radix tree lookups to a minimum. The batch size is a trade off between + * lookup reduction and stack usage. This is in the reclaim path, so we can't + * be too greedy. + */ +#define XFS_LOOKUP_BATCH 32 + +STATIC int +xfs_inode_ag_walk_grab( + struct xfs_inode *ip) +{ + struct inode *inode = VFS_I(ip); + + ASSERT(rcu_read_lock_held()); + + /* + * check for stale RCU freed inode + * + * If the inode has been reallocated, it doesn't matter if it's not in + * the AG we are walking - we are walking for writeback, so if it + * passes all the "valid inode" checks and is dirty, then we'll write + * it back anyway. If it has been reallocated and still being + * initialised, the XFS_INEW check below will catch it. + */ + spin_lock(&ip->i_flags_lock); + if (!ip->i_ino) + goto out_unlock_noent; + + /* avoid new or reclaimable inodes. Leave for reclaim code to flush */ + if (__xfs_iflags_test(ip, XFS_INEW | XFS_IRECLAIMABLE | XFS_IRECLAIM)) + goto out_unlock_noent; + spin_unlock(&ip->i_flags_lock); + + /* nothing to sync during shutdown */ + if (XFS_FORCED_SHUTDOWN(ip->i_mount)) + return EFSCORRUPTED; + + /* If we can't grab the inode, it must on it's way to reclaim. */ + if (!igrab(inode)) + return ENOENT; + + if (is_bad_inode(inode)) { + IRELE(ip); + return ENOENT; + } + + /* inode is valid */ + return 0; + +out_unlock_noent: + spin_unlock(&ip->i_flags_lock); + return ENOENT; +} + +STATIC int +xfs_inode_ag_walk( + struct xfs_mount *mp, + struct xfs_perag *pag, + int (*execute)(struct xfs_inode *ip, + struct xfs_perag *pag, int flags), + int flags) +{ + uint32_t first_index; + int last_error = 0; + int skipped; + int done; + int nr_found; + +restart: + done = 0; + skipped = 0; + first_index = 0; + nr_found = 0; + do { + struct xfs_inode *batch[XFS_LOOKUP_BATCH]; + int error = 0; + int i; + + rcu_read_lock(); + nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, + (void **)batch, first_index, + XFS_LOOKUP_BATCH); + if (!nr_found) { + rcu_read_unlock(); + break; + } + + /* + * Grab the inodes before we drop the lock. if we found + * nothing, nr == 0 and the loop will be skipped. + */ + for (i = 0; i < nr_found; i++) { + struct xfs_inode *ip = batch[i]; + + if (done || xfs_inode_ag_walk_grab(ip)) + batch[i] = NULL; + + /* + * Update the index for the next lookup. Catch + * overflows into the next AG range which can occur if + * we have inodes in the last block of the AG and we + * are currently pointing to the last inode. + * + * Because we may see inodes that are from the wrong AG + * due to RCU freeing and reallocation, only update the + * index if it lies in this AG. It was a race that lead + * us to see this inode, so another lookup from the + * same index will not find it again. + */ + if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno) + continue; + first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1); + if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino)) + done = 1; + } + + /* unlock now we've grabbed the inodes. */ + rcu_read_unlock(); + + for (i = 0; i < nr_found; i++) { + if (!batch[i]) + continue; + error = execute(batch[i], pag, flags); + IRELE(batch[i]); + if (error == EAGAIN) { + skipped++; + continue; + } + if (error && last_error != EFSCORRUPTED) + last_error = error; + } + + /* bail out if the filesystem is corrupted. */ + if (error == EFSCORRUPTED) + break; + + cond_resched(); + + } while (nr_found && !done); + + if (skipped) { + delay(1); + goto restart; + } + return last_error; +} + +int +xfs_inode_ag_iterator( + struct xfs_mount *mp, + int (*execute)(struct xfs_inode *ip, + struct xfs_perag *pag, int flags), + int flags) +{ + struct xfs_perag *pag; + int error = 0; + int last_error = 0; + xfs_agnumber_t ag; + + ag = 0; + while ((pag = xfs_perag_get(mp, ag))) { + ag = pag->pag_agno + 1; + error = xfs_inode_ag_walk(mp, pag, execute, flags); + xfs_perag_put(pag); + if (error) { + last_error = error; + if (error == EFSCORRUPTED) + break; + } + } + return XFS_ERROR(last_error); +} + +STATIC int +xfs_sync_inode_data( + struct xfs_inode *ip, + struct xfs_perag *pag, + int flags) +{ + struct inode *inode = VFS_I(ip); + struct address_space *mapping = inode->i_mapping; + int error = 0; + + if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) + goto out_wait; + + if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) { + if (flags & SYNC_TRYLOCK) + goto out_wait; + xfs_ilock(ip, XFS_IOLOCK_SHARED); + } + + error = xfs_flush_pages(ip, 0, -1, (flags & SYNC_WAIT) ? + 0 : XBF_ASYNC, FI_NONE); + xfs_iunlock(ip, XFS_IOLOCK_SHARED); + + out_wait: + if (flags & SYNC_WAIT) + xfs_ioend_wait(ip); + return error; +} + +STATIC int +xfs_sync_inode_attr( + struct xfs_inode *ip, + struct xfs_perag *pag, + int flags) +{ + int error = 0; + + xfs_ilock(ip, XFS_ILOCK_SHARED); + if (xfs_inode_clean(ip)) + goto out_unlock; + if (!xfs_iflock_nowait(ip)) { + if (!(flags & SYNC_WAIT)) + goto out_unlock; + xfs_iflock(ip); + } + + if (xfs_inode_clean(ip)) { + xfs_ifunlock(ip); + goto out_unlock; + } + + error = xfs_iflush(ip, flags); + + /* + * We don't want to try again on non-blocking flushes that can't run + * again immediately. If an inode really must be written, then that's + * what the SYNC_WAIT flag is for. + */ + if (error == EAGAIN) { + ASSERT(!(flags & SYNC_WAIT)); + error = 0; + } + + out_unlock: + xfs_iunlock(ip, XFS_ILOCK_SHARED); + return error; +} + +/* + * Write out pagecache data for the whole filesystem. + */ +STATIC int +xfs_sync_data( + struct xfs_mount *mp, + int flags) +{ + int error; + + ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0); + + error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags); + if (error) + return XFS_ERROR(error); + + xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0); + return 0; +} + +/* + * Write out inode metadata (attributes) for the whole filesystem. + */ +STATIC int +xfs_sync_attr( + struct xfs_mount *mp, + int flags) +{ + ASSERT((flags & ~SYNC_WAIT) == 0); + + return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags); +} + +STATIC int +xfs_sync_fsdata( + struct xfs_mount *mp) +{ + struct xfs_buf *bp; + + /* + * If the buffer is pinned then push on the log so we won't get stuck + * waiting in the write for someone, maybe ourselves, to flush the log. + * + * Even though we just pushed the log above, we did not have the + * superblock buffer locked at that point so it can become pinned in + * between there and here. + */ + bp = xfs_getsb(mp, 0); + if (xfs_buf_ispinned(bp)) + xfs_log_force(mp, 0); + + return xfs_bwrite(mp, bp); +} + +/* + * When remounting a filesystem read-only or freezing the filesystem, we have + * two phases to execute. This first phase is syncing the data before we + * quiesce the filesystem, and the second is flushing all the inodes out after + * we've waited for all the transactions created by the first phase to + * complete. The second phase ensures that the inodes are written to their + * location on disk rather than just existing in transactions in the log. This + * means after a quiesce there is no log replay required to write the inodes to + * disk (this is the main difference between a sync and a quiesce). + */ +/* + * First stage of freeze - no writers will make progress now we are here, + * so we flush delwri and delalloc buffers here, then wait for all I/O to + * complete. Data is frozen at that point. Metadata is not frozen, + * transactions can still occur here so don't bother flushing the buftarg + * because it'll just get dirty again. + */ +int +xfs_quiesce_data( + struct xfs_mount *mp) +{ + int error, error2 = 0; + + xfs_qm_sync(mp, SYNC_TRYLOCK); + xfs_qm_sync(mp, SYNC_WAIT); + + /* force out the newly dirtied log buffers */ + xfs_log_force(mp, XFS_LOG_SYNC); + + /* write superblock and hoover up shutdown errors */ + error = xfs_sync_fsdata(mp); + + /* make sure all delwri buffers are written out */ + xfs_flush_buftarg(mp->m_ddev_targp, 1); + + /* mark the log as covered if needed */ + if (xfs_log_need_covered(mp)) + error2 = xfs_fs_log_dummy(mp); + + /* flush data-only devices */ + if (mp->m_rtdev_targp) + XFS_bflush(mp->m_rtdev_targp); + + return error ? error : error2; +} + +STATIC void +xfs_quiesce_fs( + struct xfs_mount *mp) +{ + int count = 0, pincount; + + xfs_reclaim_inodes(mp, 0); + xfs_flush_buftarg(mp->m_ddev_targp, 0); + + /* + * This loop must run at least twice. The first instance of the loop + * will flush most meta data but that will generate more meta data + * (typically directory updates). Which then must be flushed and + * logged before we can write the unmount record. We also so sync + * reclaim of inodes to catch any that the above delwri flush skipped. + */ + do { + xfs_reclaim_inodes(mp, SYNC_WAIT); + xfs_sync_attr(mp, SYNC_WAIT); + pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1); + if (!pincount) { + delay(50); + count++; + } + } while (count < 2); +} + +/* + * Second stage of a quiesce. The data is already synced, now we have to take + * care of the metadata. New transactions are already blocked, so we need to + * wait for any remaining transactions to drain out before proceeding. + */ +void +xfs_quiesce_attr( + struct xfs_mount *mp) +{ + int error = 0; + + /* wait for all modifications to complete */ + while (atomic_read(&mp->m_active_trans) > 0) + delay(100); + + /* flush inodes and push all remaining buffers out to disk */ + xfs_quiesce_fs(mp); + + /* + * Just warn here till VFS can correctly support + * read-only remount without racing. + */ + WARN_ON(atomic_read(&mp->m_active_trans) != 0); + + /* Push the superblock and write an unmount record */ + error = xfs_log_sbcount(mp); + if (error) + xfs_warn(mp, "xfs_attr_quiesce: failed to log sb changes. " + "Frozen image may not be consistent."); + xfs_log_unmount_write(mp); + xfs_unmountfs_writesb(mp); +} + +static void +xfs_syncd_queue_sync( + struct xfs_mount *mp) +{ + queue_delayed_work(xfs_syncd_wq, &mp->m_sync_work, + msecs_to_jiffies(xfs_syncd_centisecs * 10)); +} + +/* + * Every sync period we need to unpin all items, reclaim inodes and sync + * disk quotas. We might need to cover the log to indicate that the + * filesystem is idle and not frozen. + */ +STATIC void +xfs_sync_worker( + struct work_struct *work) +{ + struct xfs_mount *mp = container_of(to_delayed_work(work), + struct xfs_mount, m_sync_work); + int error; + + if (!(mp->m_flags & XFS_MOUNT_RDONLY)) { + /* dgc: errors ignored here */ + if (mp->m_super->s_frozen == SB_UNFROZEN && + xfs_log_need_covered(mp)) + error = xfs_fs_log_dummy(mp); + else + xfs_log_force(mp, 0); + error = xfs_qm_sync(mp, SYNC_TRYLOCK); + + /* start pushing all the metadata that is currently dirty */ + xfs_ail_push_all(mp->m_ail); + } + + /* queue us up again */ + xfs_syncd_queue_sync(mp); +} + +/* + * Queue a new inode reclaim pass if there are reclaimable inodes and there + * isn't a reclaim pass already in progress. By default it runs every 5s based + * on the xfs syncd work default of 30s. Perhaps this should have it's own + * tunable, but that can be done if this method proves to be ineffective or too + * aggressive. + */ +static void +xfs_syncd_queue_reclaim( + struct xfs_mount *mp) +{ + + /* + * We can have inodes enter reclaim after we've shut down the syncd + * workqueue during unmount, so don't allow reclaim work to be queued + * during unmount. + */ + if (!(mp->m_super->s_flags & MS_ACTIVE)) + return; + + rcu_read_lock(); + if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) { + queue_delayed_work(xfs_syncd_wq, &mp->m_reclaim_work, + msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10)); + } + rcu_read_unlock(); +} + +/* + * This is a fast pass over the inode cache to try to get reclaim moving on as + * many inodes as possible in a short period of time. It kicks itself every few + * seconds, as well as being kicked by the inode cache shrinker when memory + * goes low. It scans as quickly as possible avoiding locked inodes or those + * already being flushed, and once done schedules a future pass. + */ +STATIC void +xfs_reclaim_worker( + struct work_struct *work) +{ + struct xfs_mount *mp = container_of(to_delayed_work(work), + struct xfs_mount, m_reclaim_work); + + xfs_reclaim_inodes(mp, SYNC_TRYLOCK); + xfs_syncd_queue_reclaim(mp); +} + +/* + * Flush delayed allocate data, attempting to free up reserved space + * from existing allocations. At this point a new allocation attempt + * has failed with ENOSPC and we are in the process of scratching our + * heads, looking about for more room. + * + * Queue a new data flush if there isn't one already in progress and + * wait for completion of the flush. This means that we only ever have one + * inode flush in progress no matter how many ENOSPC events are occurring and + * so will prevent the system from bogging down due to every concurrent + * ENOSPC event scanning all the active inodes in the system for writeback. + */ +void +xfs_flush_inodes( + struct xfs_inode *ip) +{ + struct xfs_mount *mp = ip->i_mount; + + queue_work(xfs_syncd_wq, &mp->m_flush_work); + flush_work_sync(&mp->m_flush_work); +} + +STATIC void +xfs_flush_worker( + struct work_struct *work) +{ + struct xfs_mount *mp = container_of(work, + struct xfs_mount, m_flush_work); + + xfs_sync_data(mp, SYNC_TRYLOCK); + xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_WAIT); +} + +int +xfs_syncd_init( + struct xfs_mount *mp) +{ + INIT_WORK(&mp->m_flush_work, xfs_flush_worker); + INIT_DELAYED_WORK(&mp->m_sync_work, xfs_sync_worker); + INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker); + + xfs_syncd_queue_sync(mp); + xfs_syncd_queue_reclaim(mp); + + return 0; +} + +void +xfs_syncd_stop( + struct xfs_mount *mp) +{ + cancel_delayed_work_sync(&mp->m_sync_work); + cancel_delayed_work_sync(&mp->m_reclaim_work); + cancel_work_sync(&mp->m_flush_work); +} + +void +__xfs_inode_set_reclaim_tag( + struct xfs_perag *pag, + struct xfs_inode *ip) +{ + radix_tree_tag_set(&pag->pag_ici_root, + XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), + XFS_ICI_RECLAIM_TAG); + + if (!pag->pag_ici_reclaimable) { + /* propagate the reclaim tag up into the perag radix tree */ + spin_lock(&ip->i_mount->m_perag_lock); + radix_tree_tag_set(&ip->i_mount->m_perag_tree, + XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino), + XFS_ICI_RECLAIM_TAG); + spin_unlock(&ip->i_mount->m_perag_lock); + + /* schedule periodic background inode reclaim */ + xfs_syncd_queue_reclaim(ip->i_mount); + + trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno, + -1, _RET_IP_); + } + pag->pag_ici_reclaimable++; +} + +/* + * We set the inode flag atomically with the radix tree tag. + * Once we get tag lookups on the radix tree, this inode flag + * can go away. + */ +void +xfs_inode_set_reclaim_tag( + xfs_inode_t *ip) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_perag *pag; + + pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino)); + spin_lock(&pag->pag_ici_lock); + spin_lock(&ip->i_flags_lock); + __xfs_inode_set_reclaim_tag(pag, ip); + __xfs_iflags_set(ip, XFS_IRECLAIMABLE); + spin_unlock(&ip->i_flags_lock); + spin_unlock(&pag->pag_ici_lock); + xfs_perag_put(pag); +} + +STATIC void +__xfs_inode_clear_reclaim( + xfs_perag_t *pag, + xfs_inode_t *ip) +{ + pag->pag_ici_reclaimable--; + if (!pag->pag_ici_reclaimable) { + /* clear the reclaim tag from the perag radix tree */ + spin_lock(&ip->i_mount->m_perag_lock); + radix_tree_tag_clear(&ip->i_mount->m_perag_tree, + XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino), + XFS_ICI_RECLAIM_TAG); + spin_unlock(&ip->i_mount->m_perag_lock); + trace_xfs_perag_clear_reclaim(ip->i_mount, pag->pag_agno, + -1, _RET_IP_); + } +} + +void +__xfs_inode_clear_reclaim_tag( + xfs_mount_t *mp, + xfs_perag_t *pag, + xfs_inode_t *ip) +{ + radix_tree_tag_clear(&pag->pag_ici_root, + XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG); + __xfs_inode_clear_reclaim(pag, ip); +} + +/* + * Grab the inode for reclaim exclusively. + * Return 0 if we grabbed it, non-zero otherwise. + */ +STATIC int +xfs_reclaim_inode_grab( + struct xfs_inode *ip, + int flags) +{ + ASSERT(rcu_read_lock_held()); + + /* quick check for stale RCU freed inode */ + if (!ip->i_ino) + return 1; + + /* + * do some unlocked checks first to avoid unnecessary lock traffic. + * The first is a flush lock check, the second is a already in reclaim + * check. Only do these checks if we are not going to block on locks. + */ + if ((flags & SYNC_TRYLOCK) && + (!ip->i_flush.done || __xfs_iflags_test(ip, XFS_IRECLAIM))) { + return 1; + } + + /* + * The radix tree lock here protects a thread in xfs_iget from racing + * with us starting reclaim on the inode. Once we have the + * XFS_IRECLAIM flag set it will not touch us. + * + * Due to RCU lookup, we may find inodes that have been freed and only + * have XFS_IRECLAIM set. Indeed, we may see reallocated inodes that + * aren't candidates for reclaim at all, so we must check the + * XFS_IRECLAIMABLE is set first before proceeding to reclaim. + */ + spin_lock(&ip->i_flags_lock); + if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) || + __xfs_iflags_test(ip, XFS_IRECLAIM)) { + /* not a reclaim candidate. */ + spin_unlock(&ip->i_flags_lock); + return 1; + } + __xfs_iflags_set(ip, XFS_IRECLAIM); + spin_unlock(&ip->i_flags_lock); + return 0; +} + +/* + * Inodes in different states need to be treated differently, and the return + * value of xfs_iflush is not sufficient to get this right. The following table + * lists the inode states and the reclaim actions necessary for non-blocking + * reclaim: + * + * + * inode state iflush ret required action + * --------------- ---------- --------------- + * bad - reclaim + * shutdown EIO unpin and reclaim + * clean, unpinned 0 reclaim + * stale, unpinned 0 reclaim + * clean, pinned(*) 0 requeue + * stale, pinned EAGAIN requeue + * dirty, delwri ok 0 requeue + * dirty, delwri blocked EAGAIN requeue + * dirty, sync flush 0 reclaim + * + * (*) dgc: I don't think the clean, pinned state is possible but it gets + * handled anyway given the order of checks implemented. + * + * As can be seen from the table, the return value of xfs_iflush() is not + * sufficient to correctly decide the reclaim action here. The checks in + * xfs_iflush() might look like duplicates, but they are not. + * + * Also, because we get the flush lock first, we know that any inode that has + * been flushed delwri has had the flush completed by the time we check that + * the inode is clean. The clean inode check needs to be done before flushing + * the inode delwri otherwise we would loop forever requeuing clean inodes as + * we cannot tell apart a successful delwri flush and a clean inode from the + * return value of xfs_iflush(). + * + * Note that because the inode is flushed delayed write by background + * writeback, the flush lock may already be held here and waiting on it can + * result in very long latencies. Hence for sync reclaims, where we wait on the + * flush lock, the caller should push out delayed write inodes first before + * trying to reclaim them to minimise the amount of time spent waiting. For + * background relaim, we just requeue the inode for the next pass. + * + * Hence the order of actions after gaining the locks should be: + * bad => reclaim + * shutdown => unpin and reclaim + * pinned, delwri => requeue + * pinned, sync => unpin + * stale => reclaim + * clean => reclaim + * dirty, delwri => flush and requeue + * dirty, sync => flush, wait and reclaim + */ +STATIC int +xfs_reclaim_inode( + struct xfs_inode *ip, + struct xfs_perag *pag, + int sync_mode) +{ + int error; + +restart: + error = 0; + xfs_ilock(ip, XFS_ILOCK_EXCL); + if (!xfs_iflock_nowait(ip)) { + if (!(sync_mode & SYNC_WAIT)) + goto out; + xfs_iflock(ip); + } + + if (is_bad_inode(VFS_I(ip))) + goto reclaim; + if (XFS_FORCED_SHUTDOWN(ip->i_mount)) { + xfs_iunpin_wait(ip); + goto reclaim; + } + if (xfs_ipincount(ip)) { + if (!(sync_mode & SYNC_WAIT)) { + xfs_ifunlock(ip); + goto out; + } + xfs_iunpin_wait(ip); + } + if (xfs_iflags_test(ip, XFS_ISTALE)) + goto reclaim; + if (xfs_inode_clean(ip)) + goto reclaim; + + /* + * Now we have an inode that needs flushing. + * + * We do a nonblocking flush here even if we are doing a SYNC_WAIT + * reclaim as we can deadlock with inode cluster removal. + * xfs_ifree_cluster() can lock the inode buffer before it locks the + * ip->i_lock, and we are doing the exact opposite here. As a result, + * doing a blocking xfs_itobp() to get the cluster buffer will result + * in an ABBA deadlock with xfs_ifree_cluster(). + * + * As xfs_ifree_cluser() must gather all inodes that are active in the + * cache to mark them stale, if we hit this case we don't actually want + * to do IO here - we want the inode marked stale so we can simply + * reclaim it. Hence if we get an EAGAIN error on a SYNC_WAIT flush, + * just unlock the inode, back off and try again. Hopefully the next + * pass through will see the stale flag set on the inode. + */ + error = xfs_iflush(ip, SYNC_TRYLOCK | sync_mode); + if (sync_mode & SYNC_WAIT) { + if (error == EAGAIN) { + xfs_iunlock(ip, XFS_ILOCK_EXCL); + /* backoff longer than in xfs_ifree_cluster */ + delay(2); + goto restart; + } + xfs_iflock(ip); + goto reclaim; + } + + /* + * When we have to flush an inode but don't have SYNC_WAIT set, we + * flush the inode out using a delwri buffer and wait for the next + * call into reclaim to find it in a clean state instead of waiting for + * it now. We also don't return errors here - if the error is transient + * then the next reclaim pass will flush the inode, and if the error + * is permanent then the next sync reclaim will reclaim the inode and + * pass on the error. + */ + if (error && error != EAGAIN && !XFS_FORCED_SHUTDOWN(ip->i_mount)) { + xfs_warn(ip->i_mount, + "inode 0x%llx background reclaim flush failed with %d", + (long long)ip->i_ino, error); + } +out: + xfs_iflags_clear(ip, XFS_IRECLAIM); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + /* + * We could return EAGAIN here to make reclaim rescan the inode tree in + * a short while. However, this just burns CPU time scanning the tree + * waiting for IO to complete and xfssyncd never goes back to the idle + * state. Instead, return 0 to let the next scheduled background reclaim + * attempt to reclaim the inode again. + */ + return 0; + +reclaim: + xfs_ifunlock(ip); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + + XFS_STATS_INC(xs_ig_reclaims); + /* + * Remove the inode from the per-AG radix tree. + * + * Because radix_tree_delete won't complain even if the item was never + * added to the tree assert that it's been there before to catch + * problems with the inode life time early on. + */ + spin_lock(&pag->pag_ici_lock); + if (!radix_tree_delete(&pag->pag_ici_root, + XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino))) + ASSERT(0); + __xfs_inode_clear_reclaim(pag, ip); + spin_unlock(&pag->pag_ici_lock); + + /* + * Here we do an (almost) spurious inode lock in order to coordinate + * with inode cache radix tree lookups. This is because the lookup + * can reference the inodes in the cache without taking references. + * + * We make that OK here by ensuring that we wait until the inode is + * unlocked after the lookup before we go ahead and free it. We get + * both the ilock and the iolock because the code may need to drop the + * ilock one but will still hold the iolock. + */ + xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL); + xfs_qm_dqdetach(ip); + xfs_iunlock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL); + + xfs_inode_free(ip); + return error; + +} + +/* + * Walk the AGs and reclaim the inodes in them. Even if the filesystem is + * corrupted, we still want to try to reclaim all the inodes. If we don't, + * then a shut down during filesystem unmount reclaim walk leak all the + * unreclaimed inodes. + */ +int +xfs_reclaim_inodes_ag( + struct xfs_mount *mp, + int flags, + int *nr_to_scan) +{ + struct xfs_perag *pag; + int error = 0; + int last_error = 0; + xfs_agnumber_t ag; + int trylock = flags & SYNC_TRYLOCK; + int skipped; + +restart: + ag = 0; + skipped = 0; + while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) { + unsigned long first_index = 0; + int done = 0; + int nr_found = 0; + + ag = pag->pag_agno + 1; + + if (trylock) { + if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) { + skipped++; + xfs_perag_put(pag); + continue; + } + first_index = pag->pag_ici_reclaim_cursor; + } else + mutex_lock(&pag->pag_ici_reclaim_lock); + + do { + struct xfs_inode *batch[XFS_LOOKUP_BATCH]; + int i; + + rcu_read_lock(); + nr_found = radix_tree_gang_lookup_tag( + &pag->pag_ici_root, + (void **)batch, first_index, + XFS_LOOKUP_BATCH, + XFS_ICI_RECLAIM_TAG); + if (!nr_found) { + done = 1; + rcu_read_unlock(); + break; + } + + /* + * Grab the inodes before we drop the lock. if we found + * nothing, nr == 0 and the loop will be skipped. + */ + for (i = 0; i < nr_found; i++) { + struct xfs_inode *ip = batch[i]; + + if (done || xfs_reclaim_inode_grab(ip, flags)) + batch[i] = NULL; + + /* + * Update the index for the next lookup. Catch + * overflows into the next AG range which can + * occur if we have inodes in the last block of + * the AG and we are currently pointing to the + * last inode. + * + * Because we may see inodes that are from the + * wrong AG due to RCU freeing and + * reallocation, only update the index if it + * lies in this AG. It was a race that lead us + * to see this inode, so another lookup from + * the same index will not find it again. + */ + if (XFS_INO_TO_AGNO(mp, ip->i_ino) != + pag->pag_agno) + continue; + first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1); + if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino)) + done = 1; + } + + /* unlock now we've grabbed the inodes. */ + rcu_read_unlock(); + + for (i = 0; i < nr_found; i++) { + if (!batch[i]) + continue; + error = xfs_reclaim_inode(batch[i], pag, flags); + if (error && last_error != EFSCORRUPTED) + last_error = error; + } + + *nr_to_scan -= XFS_LOOKUP_BATCH; + + cond_resched(); + + } while (nr_found && !done && *nr_to_scan > 0); + + if (trylock && !done) + pag->pag_ici_reclaim_cursor = first_index; + else + pag->pag_ici_reclaim_cursor = 0; + mutex_unlock(&pag->pag_ici_reclaim_lock); + xfs_perag_put(pag); + } + + /* + * if we skipped any AG, and we still have scan count remaining, do + * another pass this time using blocking reclaim semantics (i.e + * waiting on the reclaim locks and ignoring the reclaim cursors). This + * ensure that when we get more reclaimers than AGs we block rather + * than spin trying to execute reclaim. + */ + if (skipped && (flags & SYNC_WAIT) && *nr_to_scan > 0) { + trylock = 0; + goto restart; + } + return XFS_ERROR(last_error); +} + +int +xfs_reclaim_inodes( + xfs_mount_t *mp, + int mode) +{ + int nr_to_scan = INT_MAX; + + return xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan); +} + +/* + * Scan a certain number of inodes for reclaim. + * + * When called we make sure that there is a background (fast) inode reclaim in + * progress, while we will throttle the speed of reclaim via doing synchronous + * reclaim of inodes. That means if we come across dirty inodes, we wait for + * them to be cleaned, which we hope will not be very long due to the + * background walker having already kicked the IO off on those dirty inodes. + */ +void +xfs_reclaim_inodes_nr( + struct xfs_mount *mp, + int nr_to_scan) +{ + /* kick background reclaimer and push the AIL */ + xfs_syncd_queue_reclaim(mp); + xfs_ail_push_all(mp->m_ail); + + xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan); +} + +/* + * Return the number of reclaimable inodes in the filesystem for + * the shrinker to determine how much to reclaim. + */ +int +xfs_reclaim_inodes_count( + struct xfs_mount *mp) +{ + struct xfs_perag *pag; + xfs_agnumber_t ag = 0; + int reclaimable = 0; + + while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) { + ag = pag->pag_agno + 1; + reclaimable += pag->pag_ici_reclaimable; + xfs_perag_put(pag); + } + return reclaimable; +} + |
