[PATCH 08/42] fs: Remove inode lock from __generic_file_fsync()

Inode lock in __generic_file_fsync() protects sync_mapping_buffers() and
sync_inode_metadata() calls. Neither sync_mapping_buffers() nor
sync_inode_metadata() themselves need the protection by inode_lock and
both metadata buffer head writeback and inode writeback can happen
without inode lock (either in case of background writeback or sync(2)
calls). The only protection inode_lock can possibly provide is that
write(2) or other inode modifying calls cannot happen in the middle of
bh+inode writeout and thus result in writeout of inconsistent metadata.
However if writes and fsyncs race, background writeback can submit
inconsistent metadata just after fsync completed even with inode_lock
protecting fsync so this seems moot as well. So let's remove the
apparently pointless inode_lock protection.

Signed-off-by: Jan Kara <[email protected]>
---
 fs/libfs.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index 74134ba2e8d1..ed7242d614fe 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1561,7 +1561,6 @@ int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
 	if (err)
 		return err;
 
-	inode_lock(inode);
 	ret = sync_mapping_buffers(inode->i_mapping);
 	if (!(inode_state_read_once(inode) & I_DIRTY_ALL))
 		goto out;
@@ -1573,7 +1572,6 @@ int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
 		ret = err;
 
 out:
-	inode_unlock(inode);
 	/* check and advance again to catch errors after syncing out buffers */
 	err = file_check_and_advance_wb_err(file);
 	if (ret == 0)
-- 
2.51.0


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