cachefiles: Fix excess dput() after end_removing()#918
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vfsci-bot[bot] wants to merge 1 commit intovfs.base.cifrom
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cachefiles: Fix excess dput() after end_removing()#918vfsci-bot[bot] wants to merge 1 commit intovfs.base.cifrom
vfsci-bot[bot] wants to merge 1 commit intovfs.base.cifrom
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When cachefiles_cull() calls cachefiles_bury_object(), the latter eats the former's ref on the victim dentry that it obtained from cachefiles_lookup_for_cull(). However, commit 7bb1eb4 left the dput of the victim in place, resulting in occasional: WARNING: fs/dcache.c:829 at dput.part.0+0xf5/0x110, CPU#7: cachefilesd/11831 cachefiles_cull+0x8c/0xe0 [cachefiles] cachefiles_daemon_cull+0xcd/0x120 [cachefiles] cachefiles_daemon_write+0x14e/0x1d0 [cachefiles] vfs_write+0xc3/0x480 ... reports. Actually, it's worse than that: cachefiles_bury_object() eats the ref it was given - and then may continue to access the now-unref'd dentry it if it turns out to be a directory. So simply removing the aberrant dput() is not sufficient. Fix this by making cachefiles_bury_object() retain the ref itself around end_removing() if it needs to keep it and then drop the ref before returning. Fixes: bd6ede8 ("VFS/nfsd/cachefiles/ovl: introduce start_removing() and end_removing()") Reported-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: NeilBrown <neil@brown.name> cc: Paulo Alcantara <pc@manguebit.org> cc: netfs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org
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Series: https://patchwork.kernel.org/project/linux-fsdevel/list/?series=1072865
Submitter: David Howells
Version: 2
Patches: 1/1
Message-ID:
<508495.1774520128@warthog.procyon.org.uk>Base: vfs.base.ci
Lore: https://lore.kernel.org/linux-fsdevel/508495.1774520128@warthog.procyon.org.uk
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