[f2fs-dev] Patch "direct_write_fallback(): on error revert the ->ki_pos update from buffered write" has been added to the 6.1-stable tree

[f2fs-dev] Patch "direct_write_fallback(): on error revert the ->ki_pos update from buffered write" has been added to the 6.1-stable tree

[gregkh]

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This is a note to let you know that I've just added the patch titled

    direct_write_fallback(): on error revert the ->ki_pos update from buffered write

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     direct_write_fallback-on-error-revert-the-ki_pos-update-from-buffered-write.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable+bounces-188300-greg=kroah.com@vger.kernel.org Tue Oct 21 16:13:26 2025
From: Mahmoud Adam <mngyadam@amazon.de>
Date: Tue, 21 Oct 2025 09:03:40 +0200
Subject: direct_write_fallback(): on error revert the ->ki_pos update from buffered write
To: <stable@vger.kernel.org>
Cc: <gregkh@linuxfoundation.org>, <nagy@khwaternagy.com>, Al Viro <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>, Jens Axboe <axboe@kernel.dk>, Xiubo Li <xiubli@redhat.com>, Ilya Dryomov <idryomov@gmail.com>, Jeff Layton <jlayton@kernel.org>, Theodore Ts'o <tytso@mit.edu>, Andreas Dilger <adilger.kernel@dilger.ca>, Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>, Christoph Hellwig <hch@infradead.org>, "Darrick J. Wong" <djwong@kernel.org>, Trond Myklebust <trond.myklebust@hammerspace.com>, Anna Schumaker <anna@kernel.org>, "Ryusuke Konishi" <konishi.ryusuke@gmail.com>, "Matthew Wilcox (Oracle)" <willy@infradead.org>, Andrew Morton <akpm@linux-foundation.org>, "Hannes Reinecke" <hare@suse.de>, Damien Le Moal <dlemoal@kernel.org>, "Luis Chamberlain" <mcgrof@kernel.org>, <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <ceph-devel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>, <linux-ext4@vger.kernel.org>, <linux-f2fs-devel@lists.sourcefo
 rge.net>, <linux-xfs@vger.kernel.org>, <linux-nfs@vger.kernel.org>, <linux-nilfs@vger.kernel.org>, <linux-mm@kvack.org>
Message-ID: <20251021070353.96705-7-mngyadam@amazon.de>

From: Al Viro <viro@zeniv.linux.org.uk>

commit 8287474aa5ffb41df52552c4ae4748e791d2faf2 upstream.

If we fail filemap_write_and_wait_range() on the range the buffered write went
into, we only report the "number of bytes which we direct-written", to quote
the comment in there.  Which is fine, but buffered write has already advanced
iocb->ki_pos, so we need to roll that back.  Otherwise we end up with e.g.
write(2) advancing position by more than the amount it reports having written.

Fixes: 182c25e9c157 "filemap: update ki_pos in generic_perform_write"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Message-Id: <20230827214518.GU3390869@ZenIV>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Mahmoud Adam <mngyadam@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/libfs.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1615,6 +1615,7 @@ ssize_t direct_write_fallback(struct kio
 		 * We don't know how much we wrote, so just return the number of
 		 * bytes which were direct-written
 		 */
+		iocb->ki_pos -= buffered_written;
 		if (direct_written)
 			return direct_written;
 		return err;


Patches currently in stable-queue which might be from mngyadam@amazon.de are

queue-6.1/block-fix-race-between-set_blocksize-and-read-paths.patch
queue-6.1/filemap-add-a-kiocb_invalidate_pages-helper.patch
queue-6.1/fs-factor-out-a-direct_write_fallback-helper.patch
queue-6.1/direct_write_fallback-on-error-revert-the-ki_pos-update-from-buffered-write.patch
queue-6.1/filemap-update-ki_pos-in-generic_perform_write.patch
queue-6.1/filemap-add-a-kiocb_invalidate_post_direct_write-helper.patch
queue-6.1/nilfs2-fix-deadlock-warnings-caused-by-lock-dependency-in-init_nilfs.patch
queue-6.1/block-open-code-__generic_file_write_iter-for-blkdev-writes.patch


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