3.16.78-rc1 review patch. If anyone has any objections, please let me know.
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From: Pavel Shilovsky pshilov@microsoft.com
commit 1a67c415965752879e2e9fad407bc44fc7f25f23 upstream.
Currently the code assumes that if a file info entry belongs to lists of open file handles of an inode and a tcon then it has non-zero reference. The recent changes broke that assumption when putting the last reference of the file info. There may be a situation when a file is being deleted but nothing prevents another thread to reference it again and start using it. This happens because we do not hold the inode list lock while checking the number of references of the file info structure. Fix this by doing the proper locking when doing the check.
Fixes: 487317c99477d ("cifs: add spinlock for the openFileList to cifsInodeInfo") Fixes: cb248819d209d ("cifs: use cifsInodeInfo->open_file_lock while iterating to avoid a panic") Reviewed-by: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/cifs/file.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -398,10 +398,11 @@ void _cifsFileInfo_put(struct cifsFileIn bool oplock_break_cancelled;
spin_lock(&tcon->open_file_lock); - + spin_lock(&cifsi->open_file_lock); spin_lock(&cifs_file->file_info_lock); if (--cifs_file->count > 0) { spin_unlock(&cifs_file->file_info_lock); + spin_unlock(&cifsi->open_file_lock); spin_unlock(&tcon->open_file_lock); return; } @@ -414,9 +415,7 @@ void _cifsFileInfo_put(struct cifsFileIn cifs_add_pending_open_locked(&fid, cifs_file->tlink, &open);
/* remove it from the lists */ - spin_lock(&cifsi->open_file_lock); list_del(&cifs_file->flist); - spin_unlock(&cifsi->open_file_lock); list_del(&cifs_file->tlist);
if (list_empty(&cifsi->openFileList)) { @@ -432,6 +431,7 @@ void _cifsFileInfo_put(struct cifsFileIn cifs_set_oplock_level(cifsi, 0); }
+ spin_unlock(&cifsi->open_file_lock); spin_unlock(&tcon->open_file_lock);
oplock_break_cancelled = wait_oplock_handler ?