diff options
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_icache.c | 128 |
1 files changed, 35 insertions, 93 deletions
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index f4e7b98d9639..dc90a81abb1a 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -141,11 +141,8 @@ xfs_inode_free( } /* - * 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 periodic sync 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. + * Queue background inode reclaim work if there are reclaimable inodes and there + * isn't reclaim work already scheduled or in progress. */ static void xfs_reclaim_work_queue( @@ -600,48 +597,31 @@ out_destroy: } /* - * Look up an inode by number in the given file system. - * The inode is looked up in the cache held in each AG. - * If the inode is found in the cache, initialise the vfs inode - * if necessary. + * Look up an inode by number in the given file system. The inode is looked up + * in the cache held in each AG. If the inode is found in the cache, initialise + * the vfs inode if necessary. * - * If it is not in core, read it in from the file system's device, - * add it to the cache and initialise the vfs inode. + * If it is not in core, read it in from the file system's device, add it to the + * cache and initialise the vfs inode. * * The inode is locked according to the value of the lock_flags parameter. - * This flag parameter indicates how and if the inode's IO lock and inode lock - * should be taken. - * - * mp -- the mount point structure for the current file system. It points - * to the inode hash table. - * tp -- a pointer to the current transaction if there is one. This is - * simply passed through to the xfs_iread() call. - * ino -- the number of the inode desired. This is the unique identifier - * within the file system for the inode being requested. - * lock_flags -- flags indicating how to lock the inode. See the comment - * for xfs_ilock() for a list of valid values. + * Inode lookup is only done during metadata operations and not as part of the + * data IO path. Hence we only allow locking of the XFS_ILOCK during lookup. */ int xfs_iget( - xfs_mount_t *mp, - xfs_trans_t *tp, - xfs_ino_t ino, - uint flags, - uint lock_flags, - xfs_inode_t **ipp) + struct xfs_mount *mp, + struct xfs_trans *tp, + xfs_ino_t ino, + uint flags, + uint lock_flags, + struct xfs_inode **ipp) { - xfs_inode_t *ip; - int error; - xfs_perag_t *pag; - xfs_agino_t agino; + struct xfs_inode *ip; + struct xfs_perag *pag; + xfs_agino_t agino; + int error; - /* - * xfs_reclaim_inode() uses the ILOCK to ensure an inode - * doesn't get freed while it's being referenced during a - * radix tree traversal here. It assumes this function - * aqcuires only the ILOCK (and therefore it has no need to - * involve the IOLOCK in this synchronization). - */ ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0); /* reject inode numbers outside existing AGs */ @@ -758,15 +738,7 @@ xfs_inode_walk_ag_grab( 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. - */ + /* Check for stale RCU freed inode */ spin_lock(&ip->i_flags_lock); if (!ip->i_ino) goto out_unlock_noent; @@ -1044,43 +1016,16 @@ xfs_reclaim_inode_grab( } /* - * Inodes in different states need to be treated differently. The following - * table lists the inode states and the reclaim actions necessary: - * - * 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, async - requeue - * dirty, sync 0 reclaim + * Inode reclaim is non-blocking, so the default action if progress cannot be + * made is to "requeue" the inode for reclaim by unlocking it and clearing the + * XFS_IRECLAIM flag. If we are in a shutdown state, we don't care about + * blocking anymore and hence we can wait for the inode to be able to reclaim + * it. * - * (*) dgc: I don't think the clean, pinned state is possible but it gets - * handled anyway given the order of checks implemented. - * - * 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. - * - * Note that because the inode is flushed delayed write by AIL pushing, 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 the AIL first before trying to reclaim inodes to - * minimise the amount of time spent waiting. For background relaim, we only - * bother to reclaim clean inodes anyway. - * - * Hence the order of actions after gaining the locks should be: - * bad => reclaim - * shutdown => unpin and reclaim - * pinned, async => requeue - * pinned, sync => unpin - * stale => reclaim - * clean => reclaim - * dirty, async => requeue - * dirty, sync => flush, wait and reclaim + * We do no IO here - if callers require inodes to be cleaned they must push the + * AIL first to trigger writeback of dirty inodes. This enables writeback to be + * done in the background in a non-blocking manner, and enables memory reclaim + * to make progress without blocking. */ static void xfs_reclaim_inode( @@ -1271,13 +1216,11 @@ xfs_reclaim_inodes( } /* - * 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. + * The shrinker infrastructure determines how many inodes we should scan for + * reclaim. We want as many clean inodes ready to reclaim as possible, so we + * push the AIL here. We also want to proactively free up memory if we can to + * minimise the amount of work memory reclaim has to do so we kick the + * background reclaim if it isn't already scheduled. */ long xfs_reclaim_inodes_nr( @@ -1390,8 +1333,7 @@ xfs_inode_matches_eofb( * 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. + * goes low. */ void xfs_reclaim_worker( |