Re: [PATCH RFC 9/9] fs: don't strand I_METADATA_WRITEBACK inodes outside the LRU

[sashiko-bot@kernel.org]

> Since commit c474bc56b6d1 ("fs: Provide way for filesystem to wait for
> metadata writeback") ext2, ext4 without a journal, fat, udf and minix
> set I_METADATA_WRITEBACK on an inode whose metadata was copied into a
> buffer that might not have reached the disk yet. Only data integrity
> writeback, i.e. fsync() and friends, clears it again. The flusher and
> sync(2) leave it alone. So a clean, unused inode keeps the bit around.
> 
> inode_lru_isolate() treats every state bit other than I_REFERENCED as a
> reason not to reclaim the inode right now. It takes the inode off the
> LRU and relies on iput(), writeback completion or the removal of the
> last page from the page cache to put it back once the reason is gone.
> 
> But I_METADATA_WRITEBACK doesn't go away on its own. Using the inode
> again puts it back on the LRU with the bit still set and the next scan
> takes it off again. So neither memory pressure nor drop_caches can free
> [ ... ]
> 
> Fixes: c474bc56b6d1 ("fs: Provide way for filesystem to wait for metadata writeback")
> Cc: stable@vger.kernel.org # v7.3; see patch description
> Reported-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261029-work-inode-metadata_writeback-v1-0-7d6c678a585d@kernel.org?part=9