btrfs: file_remove_privs needs an exclusive lock in direct io write

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This was noticed by Miklos that file_remove_privs might call into
notify_change(), which requires to hold an exclusive lock. The problem
exists in FUSE and btrfs. We can fix it without any additional helpers
from VFS, in case the privileges would need to be dropped, change the
lock type to be exclusive and redo the loop.

Fixes: e9adabb971 ("btrfs: use shared lock for direct writes within EOF")
CC: Miklos Szeredi <miklos@szeredi.hu>
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Bernd Schubert 2023-09-06 17:59:03 +02:00 • committed by David Sterba

parent 06ed09351b

commit 9af86694fd

1 changed files with 14 additions and 2 deletions

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fs/btrfs/file.c

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