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author | Filipe Manana <fdmanana@suse.com> | 2021-08-31 15:30:39 +0100 |
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committer | David Sterba <dsterba@suse.com> | 2021-10-26 19:08:01 +0200 |
commit | 5328b2a7ff3a28ec0f581f5f4e904f4db1612ac9 (patch) | |
tree | ac71a441e094b4074af16d0045204ba3c6ce42e9 /fs/btrfs/tree-log.c | |
parent | a5c733a4b6a96f58d833736c56ba3187106b7a5f (diff) | |
download | linux-5328b2a7ff3a28ec0f581f5f4e904f4db1612ac9.tar.bz2 |
btrfs: avoid attempt to drop extents when logging inode for the first time
When logging an extent, in the fast fsync path, we always attempt do drop
or trim any existing extents with a range that match or overlap the range
of the extent we are about to log. We do that through a call to
btrfs_drop_extents().
However this is not needed when we are logging the inode for the first
time in the current transaction, since we have no inode items of the
inode in the log tree. Calling btrfs_drop_extents() does a deletion search
on the log tree, which is expensive when we have concurrent tasks
accessing the log tree because a deletion search always acquires a write
lock on the extent buffers at levels 2, 1 and 0, adding significant lock
contention, specially taking into account the height of a log tree rarely
(if ever) goes beyond 2 or 3, due to its short life.
So skip the call to btrfs_drop_extents() when the inode was not previously
logged in the current transaction.
This patch is part of a patch set comprised of the following patches:
btrfs: check if a log tree exists at inode_logged()
btrfs: remove no longer needed checks for NULL log context
btrfs: do not log new dentries when logging that a new name exists
btrfs: always update the logged transaction when logging new names
btrfs: avoid expensive search when dropping inode items from log
btrfs: add helper to truncate inode items when logging inode
btrfs: avoid expensive search when truncating inode items from the log
btrfs: avoid search for logged i_size when logging inode if possible
btrfs: avoid attempt to drop extents when logging inode for the first time
btrfs: do not commit delayed inode when logging a file in full sync mode
This is patch 9/10 and test results are listed in the change log of the
last patch in the set.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tree-log.c')
-rw-r--r-- | fs/btrfs/tree-log.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 6684fccee236..951f7b8f85b7 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -4375,14 +4375,25 @@ static int log_one_extent(struct btrfs_trans_handle *trans, if (ret) return ret; - drop_args.path = path; - drop_args.start = em->start; - drop_args.end = em->start + em->len; - drop_args.replace_extent = true; - drop_args.extent_item_size = sizeof(*fi); - ret = btrfs_drop_extents(trans, log, inode, &drop_args); - if (ret) - return ret; + /* + * If this is the first time we are logging the inode in the current + * transaction, we can avoid btrfs_drop_extents(), which is expensive + * because it does a deletion search, which always acquires write locks + * for extent buffers at levels 2, 1 and 0. This not only wastes time + * but also adds significant contention in a log tree, since log trees + * are small, with a root at level 2 or 3 at most, due to their short + * life span. + */ + if (inode_logged(trans, inode)) { + drop_args.path = path; + drop_args.start = em->start; + drop_args.end = em->start + em->len; + drop_args.replace_extent = true; + drop_args.extent_item_size = sizeof(*fi); + ret = btrfs_drop_extents(trans, log, inode, &drop_args); + if (ret) + return ret; + } if (!drop_args.extent_inserted) { key.objectid = btrfs_ino(inode); |