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| author | Jeff Layton | 2014-04-30 15:31:47 +0200 |
|---|---|---|
| committer | Steve French | 2014-05-21 19:18:05 +0200 |
| commit | 4f73c7d342d57d065bdbc0995cb56d8d1701b0c0 (patch) | |
| tree | 6933002e316475c879d702ffbb733a24ba4f0561 /fs/cifs/file.c | |
| parent | cifs: new helper function: cifs_revalidate_mapping (diff) | |
| download | kernel-qcow2-linux-4f73c7d342d57d065bdbc0995cb56d8d1701b0c0.tar.gz kernel-qcow2-linux-4f73c7d342d57d065bdbc0995cb56d8d1701b0c0.tar.xz kernel-qcow2-linux-4f73c7d342d57d065bdbc0995cb56d8d1701b0c0.zip | |
cifs: fix potential races in cifs_revalidate_mapping
The handling of the CIFS_INO_INVALID_MAPPING flag is racy. It's possible
for two tasks to attempt to revalidate the mapping at the same time. The
first sees that CIFS_INO_INVALID_MAPPING is set. It clears the flag and
then calls invalidate_inode_pages2 to start shooting down the pagecache.
While that's going on, another task checks the flag and sees that it's
clear. It then ends up trusting the pagecache to satisfy a read when it
shouldn't.
Fix this by adding a bitlock to ensure that the clearing of the flag is
atomic with respect to the actual cache invalidation. Also, move the
other existing users of cifs_invalidate_mapping to use a new
cifs_zap_mapping() function that just sets the INVALID_MAPPING bit and
then uses the standard codepath to handle the invalidation.
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs/file.c')
| -rw-r--r-- | fs/cifs/file.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c index c8a570e87900..208f56eca4bf 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -335,7 +335,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file, spin_unlock(&cifs_file_list_lock); if (fid->purge_cache) - cifs_invalidate_mapping(inode); + cifs_zap_mapping(inode); file->private_data = cfile; return cfile; @@ -1529,7 +1529,7 @@ cifs_setlk(struct file *file, struct file_lock *flock, __u32 type, */ if (!CIFS_CACHE_WRITE(CIFS_I(inode)) && CIFS_CACHE_READ(CIFS_I(inode))) { - cifs_invalidate_mapping(inode); + cifs_zap_mapping(inode); cifs_dbg(FYI, "Set no oplock for inode=%p due to mand locks\n", inode); CIFS_I(inode)->oplock = 0; @@ -2218,7 +2218,7 @@ int cifs_strict_fsync(struct file *file, loff_t start, loff_t end, file->f_path.dentry->d_name.name, datasync); if (!CIFS_CACHE_READ(CIFS_I(inode))) { - rc = cifs_invalidate_mapping(inode); + rc = cifs_zap_mapping(inode); if (rc) { cifs_dbg(FYI, "rc: %d during invalidate phase\n", rc); rc = 0; /* don't care about it in fsync */ @@ -2649,7 +2649,7 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov, * request comes - break it on the client to prevent reading * an old data. */ - cifs_invalidate_mapping(inode); + cifs_zap_mapping(inode); cifs_dbg(FYI, "Set no oplock for inode=%p after a write operation\n", inode); cinode->oplock = 0; @@ -3112,7 +3112,7 @@ int cifs_file_strict_mmap(struct file *file, struct vm_area_struct *vma) xid = get_xid(); if (!CIFS_CACHE_READ(CIFS_I(inode))) { - rc = cifs_invalidate_mapping(inode); + rc = cifs_zap_mapping(inode); if (rc) return rc; } @@ -3670,7 +3670,7 @@ void cifs_oplock_break(struct work_struct *work) if (!CIFS_CACHE_READ(cinode)) { rc = filemap_fdatawait(inode->i_mapping); mapping_set_error(inode->i_mapping, rc); - cifs_invalidate_mapping(inode); + cifs_zap_mapping(inode); } cifs_dbg(FYI, "Oplock flush inode %p rc %d\n", inode, rc); } |