[Devel] [PATCH hci-8.1 2/3] fs/fuse: move the close_wait handling of fuse_release() into a helper

[no-reply at sashiko.virtuozzo.com]

> Move all the close_wait handling of fuse_release() into a new helper
> fuse_release_close_wait(), and restore the !close_wait case to the
> mainline behavior except the FMODE_WRITE check.
> 
> Unify the code paths: unconditionally remove the file from
> fi->write_files and wait until we hold the last reference. Decrement
> fi->num_openers under the inode lock, which detects the last open.
> This fixes two racing releasers both reading num_openers == 0 and
> calling kio's file_close twice, possible because the decrement was
> done early under fi->lock while the check ran later under the inode
> lock:
> 
>   releaser A                      releaser B
>   ----------                      ----------
>   --fi->num_openers  (2 -> 1)
>                                   --fi->num_openers  (1 -> 0)
>   inode_lock()
>   num_openers == 0 -> file_close()
>   inode_unlock()
>                                   inode_lock()
>                                   num_openers == 0 -> file_close()
> 
> The atomic decrement under the inode lock also matches the increment
> in fuse_open_close_wait() for !writeback_cache files.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-147878
> 
> Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20260930-close-wait-rework-v2-v1-0-f8062178544a@virtuozzo.com?part=2