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authorFilipe Manana <fdmanana@suse.com>2021-07-29 18:52:46 +0100
committerDavid Sterba <dsterba@suse.com>2021-08-23 13:19:15 +0200
commit8be2ba2e0e11ade6ab96d8887dbb12abbd3540f4 (patch)
tree02581cd7320cd6f7dfced8d94d50d0f3723759e3 /fs/btrfs
parent5b9b26f5d0b88b74001dcfe4ab8a8f2f4e744112 (diff)
btrfs: avoid unnecessarily logging directories that had no changes
There are several cases where when logging an inode we need to log its parent directories or logging subdirectories when logging a directory. There are cases however where we end up logging a directory even if it was not changed in the current transaction, no dentries added or removed since the last transaction. While this is harmless from a functional point of view, it is a waste time as it brings no advantage. One example where this is triggered is the following: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt $ mkdir /mnt/A $ mkdir /mnt/B $ mkdir /mnt/C $ touch /mnt/A/foo $ ln /mnt/A/foo /mnt/B/bar $ ln /mnt/A/foo /mnt/C/baz $ sync $ rm -f /mnt/A/foo $ xfs_io -c "fsync" /mnt/B/bar This last fsync ends up logging directories A, B and C, however we only need to log directory A, as B and C were not changed since the last transaction commit. So fix this by changing need_log_inode(), to return false in case the given inode is a directory and has a ->last_trans value smaller than the current transaction's ID. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/tree-log.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1ce7e4480256..a1aaa1b8bd5c 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -5614,6 +5614,13 @@ static bool need_log_inode(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode)
{
/*
+ * If a directory was not modified, no dentries added or removed, we can
+ * and should avoid logging it.
+ */
+ if (S_ISDIR(inode->vfs_inode.i_mode) && inode->last_trans < trans->transid)
+ return false;
+
+ /*
* If this inode does not have new/updated/deleted xattrs since the last
* time it was logged and is flagged as logged in the current transaction,
* we can skip logging it. As for new/deleted names, those are updated in