On 2017年09月14日 02:25, Liu Bo wrote:
It doens't make sense to backup tree roots when doing fsync, since
during fsync those tree roots have not been consistent on disk.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Reviewed-by: Qu Wenruo <quwenruo.btrfs@xxxxxxx>
With a pit can be improved.
---
fs/btrfs/disk-io.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 79ac228..a145a88 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3668,7 +3668,14 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
u64 flags;
do_barriers = !btrfs_test_opt(fs_info, NOBARRIER);
- backup_super_roots(fs_info);
+
+ /*
+ * max_mirrors == 0 indicates we're from commit_transaction,
+ * not from fsync where the tree roots in fs_info have not
+ * been consistent on disk.
+ */
+ if (max_mirrors == 0)
+ backup_super_roots(fs_info);
BTW, the @max_mirrors naming here is really confusing.
Normally I would expect max_mirrors == 0 means we don't need to backup
super roots...
And since there are only two callers it won't be a big thing to change.
Thanks,
Qu
sb = fs_info->super_for_commit;
dev_item = &sb->dev_item;
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