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authorFilipe Manana <fdmanana@suse.com>2021-01-27 10:34:55 +0000
committerDavid Sterba <dsterba@suse.com>2021-02-08 22:59:00 +0100
commite593e54ed1f643f5007ab4656188b7c3c9a9cb11 (patch)
treedb446fa3cae240b3f37538cfa700f9a6debbb174 /fs
parentddffcf6fb5ac54ffcd7e90b10554d89dbd10b47b (diff)
btrfs: stop setting nbytes when filling inode item for logging
When we fill an inode item for logging we are setting its nbytes field with the value returned by inode_get_bytes() (a VFS API), however we do not need it because it is not used during log replay. In fact, for fast fsyncs, when we call inode_get_bytes() we may even get an outdated value for nbytes because the nbytes field of the inode is only updated when ordered extents complete, and a fast fsync only waits for writeback to complete, it does not wait for ordered extent completion. So just remove the setup of nbytes and add an explicit comment mentioning why we do not set it. This also avoids adding contention on the inode's i_lock (VFS) with concurrent stat() calls, since that spinlock is used by inode_get_bytes() which is also called by our stat callback (btrfs_getattr()). This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/tree-log.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 5d87afc6058a..be62759f0aac 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3858,7 +3858,14 @@ static void fill_inode_item(struct btrfs_trans_handle *trans,
btrfs_set_token_timespec_nsec(&token, &item->ctime,
inode->i_ctime.tv_nsec);
- btrfs_set_token_inode_nbytes(&token, item, inode_get_bytes(inode));
+ /*
+ * We do not need to set the nbytes field, in fact during a fast fsync
+ * its value may not even be correct, since a fast fsync does not wait
+ * for ordered extent completion, which is where we update nbytes, it
+ * only waits for writeback to complete. During log replay as we find
+ * file extent items and replay them, we adjust the nbytes field of the
+ * inode item in subvolume tree as needed (see overwrite_item()).
+ */
btrfs_set_token_inode_sequence(&token, item, inode_peek_iversion(inode));
btrfs_set_token_inode_transid(&token, item, trans->transid);