From c8e20be020f234c8d492927a424a7d8bbefd5b5d Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Sun, 10 Jan 2010 23:51:45 +0000 Subject: xfs: reclaim inodes under a write lock Make the inode tree reclaim walk exclusive to avoid races with concurrent sync walkers and lookups. This is a version of a patch posted by Christoph Hellwig that avoids all the code duplication. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_sync.c | 154 ++++++++++++++++++++------------------------ 1 file changed, 69 insertions(+), 85 deletions(-) (limited to 'fs/xfs/linux-2.6/xfs_sync.c') diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c index 6fed97a8cd3..e19d25555c3 100644 --- a/fs/xfs/linux-2.6/xfs_sync.c +++ b/fs/xfs/linux-2.6/xfs_sync.c @@ -65,7 +65,6 @@ xfs_inode_ag_lookup( * as the tree is sparse and a gang lookup walks to find * the number of objects requested. */ - read_lock(&pag->pag_ici_lock); if (tag == XFS_ICI_NO_TAG) { nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void **)&ip, *first_index, 1); @@ -74,7 +73,7 @@ xfs_inode_ag_lookup( (void **)&ip, *first_index, 1, tag); } if (!nr_found) - goto unlock; + return NULL; /* * Update the index for the next lookup. Catch overflows @@ -84,13 +83,8 @@ xfs_inode_ag_lookup( */ *first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1); if (*first_index < XFS_INO_TO_AGINO(mp, ip->i_ino)) - goto unlock; - + return NULL; return ip; - -unlock: - read_unlock(&pag->pag_ici_lock); - return NULL; } STATIC int @@ -100,7 +94,8 @@ xfs_inode_ag_walk( int (*execute)(struct xfs_inode *ip, struct xfs_perag *pag, int flags), int flags, - int tag) + int tag, + int exclusive) { struct xfs_perag *pag = &mp->m_perag[ag]; uint32_t first_index; @@ -114,10 +109,20 @@ restart: int error = 0; xfs_inode_t *ip; + if (exclusive) + write_lock(&pag->pag_ici_lock); + else + read_lock(&pag->pag_ici_lock); ip = xfs_inode_ag_lookup(mp, pag, &first_index, tag); - if (!ip) + if (!ip) { + if (exclusive) + write_unlock(&pag->pag_ici_lock); + else + read_unlock(&pag->pag_ici_lock); break; + } + /* execute releases pag->pag_ici_lock */ error = execute(ip, pag, flags); if (error == EAGAIN) { skipped++; @@ -125,9 +130,8 @@ restart: } if (error) last_error = error; - /* - * bail out if the filesystem is corrupted. - */ + + /* bail out if the filesystem is corrupted. */ if (error == EFSCORRUPTED) break; @@ -148,7 +152,8 @@ xfs_inode_ag_iterator( int (*execute)(struct xfs_inode *ip, struct xfs_perag *pag, int flags), int flags, - int tag) + int tag, + int exclusive) { int error = 0; int last_error = 0; @@ -157,7 +162,8 @@ xfs_inode_ag_iterator( for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) { if (!mp->m_perag[ag].pag_ici_init) continue; - error = xfs_inode_ag_walk(mp, ag, execute, flags, tag); + error = xfs_inode_ag_walk(mp, ag, execute, flags, tag, + exclusive); if (error) { last_error = error; if (error == EFSCORRUPTED) @@ -181,11 +187,7 @@ xfs_sync_inode_valid( return EFSCORRUPTED; } - /* - * If we can't get a reference on the inode, it must be in reclaim. - * Leave it for the reclaim code to flush. Also avoid inodes that - * haven't been fully initialised. - */ + /* If we can't get a reference on the inode, it must be in reclaim. */ if (!igrab(inode)) { read_unlock(&pag->pag_ici_lock); return ENOENT; @@ -282,7 +284,7 @@ xfs_sync_data( ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0); error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags, - XFS_ICI_NO_TAG); + XFS_ICI_NO_TAG, 0); if (error) return XFS_ERROR(error); @@ -304,7 +306,7 @@ xfs_sync_attr( ASSERT((flags & ~SYNC_WAIT) == 0); return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags, - XFS_ICI_NO_TAG); + XFS_ICI_NO_TAG, 0); } STATIC int @@ -664,60 +666,6 @@ xfs_syncd_stop( kthread_stop(mp->m_sync_task); } -STATIC int -xfs_reclaim_inode( - xfs_inode_t *ip, - int sync_mode) -{ - xfs_perag_t *pag = xfs_get_perag(ip->i_mount, ip->i_ino); - - /* The hash lock here protects a thread in xfs_iget_core from - * racing with us on linking the inode back with a vnode. - * Once we have the XFS_IRECLAIM flag set it will not touch - * us. - */ - write_lock(&pag->pag_ici_lock); - spin_lock(&ip->i_flags_lock); - if (__xfs_iflags_test(ip, XFS_IRECLAIM) || - !__xfs_iflags_test(ip, XFS_IRECLAIMABLE)) { - spin_unlock(&ip->i_flags_lock); - write_unlock(&pag->pag_ici_lock); - return -EAGAIN; - } - __xfs_iflags_set(ip, XFS_IRECLAIM); - spin_unlock(&ip->i_flags_lock); - write_unlock(&pag->pag_ici_lock); - xfs_put_perag(ip->i_mount, pag); - - /* - * If the inode is still dirty, then flush it out. If the inode - * is not in the AIL, then it will be OK to flush it delwri as - * long as xfs_iflush() does not keep any references to the inode. - * We leave that decision up to xfs_iflush() since it has the - * knowledge of whether it's OK to simply do a delwri flush of - * the inode or whether we need to wait until the inode is - * pulled from the AIL. - * We get the flush lock regardless, though, just to make sure - * we don't free it while it is being flushed. - */ - xfs_ilock(ip, XFS_ILOCK_EXCL); - xfs_iflock(ip); - - /* - * In the case of a forced shutdown we rely on xfs_iflush() to - * wait for the inode to be unpinned before returning an error. - */ - if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) { - /* synchronize with xfs_iflush_done */ - xfs_iflock(ip); - xfs_ifunlock(ip); - } - - xfs_iunlock(ip, XFS_ILOCK_EXCL); - xfs_ireclaim(ip); - return 0; -} - void __xfs_inode_set_reclaim_tag( struct xfs_perag *pag, @@ -760,19 +708,55 @@ __xfs_inode_clear_reclaim_tag( } STATIC int -xfs_reclaim_inode_now( +xfs_reclaim_inode( struct xfs_inode *ip, struct xfs_perag *pag, - int flags) + int sync_mode) { - /* ignore if already under reclaim */ - if (xfs_iflags_test(ip, XFS_IRECLAIM)) { - read_unlock(&pag->pag_ici_lock); + /* + * 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. + */ + spin_lock(&ip->i_flags_lock); + ASSERT_ALWAYS(__xfs_iflags_test(ip, XFS_IRECLAIMABLE)); + if (__xfs_iflags_test(ip, XFS_IRECLAIM)) { + /* ignore as it is already under reclaim */ + spin_unlock(&ip->i_flags_lock); + write_unlock(&pag->pag_ici_lock); return 0; } - read_unlock(&pag->pag_ici_lock); + __xfs_iflags_set(ip, XFS_IRECLAIM); + spin_unlock(&ip->i_flags_lock); + write_unlock(&pag->pag_ici_lock); + + /* + * If the inode is still dirty, then flush it out. If the inode + * is not in the AIL, then it will be OK to flush it delwri as + * long as xfs_iflush() does not keep any references to the inode. + * We leave that decision up to xfs_iflush() since it has the + * knowledge of whether it's OK to simply do a delwri flush of + * the inode or whether we need to wait until the inode is + * pulled from the AIL. + * We get the flush lock regardless, though, just to make sure + * we don't free it while it is being flushed. + */ + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_iflock(ip); - return xfs_reclaim_inode(ip, flags); + /* + * In the case of a forced shutdown we rely on xfs_iflush() to + * wait for the inode to be unpinned before returning an error. + */ + if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) { + /* synchronize with xfs_iflush_done */ + xfs_iflock(ip); + xfs_ifunlock(ip); + } + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + xfs_ireclaim(ip); + return 0; } int @@ -780,6 +764,6 @@ xfs_reclaim_inodes( xfs_mount_t *mp, int mode) { - return xfs_inode_ag_iterator(mp, xfs_reclaim_inode_now, mode, - XFS_ICI_RECLAIM_TAG); + return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode, + XFS_ICI_RECLAIM_TAG, 1); } -- cgit v1.2.3-70-g09d2 From 018027be90a6946e8cf3f9b17b5582384f7ed117 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Sun, 10 Jan 2010 23:51:46 +0000 Subject: xfs: Avoid inodes in reclaim when flushing from inode cache The reclaim code will handle flushing of dirty inodes before reclaim occurs, so avoid them when determining whether an inode is a candidate for flushing to disk when walking the radix trees. This is based on a test patch from Christoph Hellwig. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_sync.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) (limited to 'fs/xfs/linux-2.6/xfs_sync.c') diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c index e19d25555c3..1f5e4bb5e97 100644 --- a/fs/xfs/linux-2.6/xfs_sync.c +++ b/fs/xfs/linux-2.6/xfs_sync.c @@ -180,26 +180,31 @@ xfs_sync_inode_valid( struct xfs_perag *pag) { struct inode *inode = VFS_I(ip); + int error = EFSCORRUPTED; /* nothing to sync during shutdown */ - if (XFS_FORCED_SHUTDOWN(ip->i_mount)) { - read_unlock(&pag->pag_ici_lock); - return EFSCORRUPTED; - } + if (XFS_FORCED_SHUTDOWN(ip->i_mount)) + goto out_unlock; - /* If we can't get a reference on the inode, it must be in reclaim. */ - if (!igrab(inode)) { - read_unlock(&pag->pag_ici_lock); - return ENOENT; - } - read_unlock(&pag->pag_ici_lock); + /* avoid new or reclaimable inodes. Leave for reclaim code to flush */ + error = ENOENT; + if (xfs_iflags_test(ip, XFS_INEW | XFS_IRECLAIMABLE | XFS_IRECLAIM)) + goto out_unlock; - if (is_bad_inode(inode) || xfs_iflags_test(ip, XFS_INEW)) { + /* If we can't grab the inode, it must on it's way to reclaim. */ + if (!igrab(inode)) + goto out_unlock; + + if (is_bad_inode(inode)) { IRELE(ip); - return ENOENT; + goto out_unlock; } - return 0; + /* inode is valid */ + error = 0; +out_unlock: + read_unlock(&pag->pag_ici_lock); + return error; } STATIC int -- cgit v1.2.3-70-g09d2