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CIFS: Do not permit write to a range mandatory locked with a read lock 

We don't need to permit a write to the area locked with a read lock
by any process including the process that issues the write.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Pavel Shilovsky 2012-11-27 18:38:53 +04:00 committed by Steve French
parent eb1b3fa5cd
commit 081c0414dc
2 changed files with 19 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/cifs/cifsproto.h
View File

@ -186,7 +186,7 @@ extern void cifs_mark_open_files_invalid(struct cifs_tcon *tcon);
extern bool cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset,
__u64 length, __u8 type,
struct cifsLockInfo **conf_lock,
bool rw_check);
int rw_check);
extern void cifs_add_pending_open(struct cifs_fid *fid,
struct tcon_link *tlink,
struct cifs_pending_open *open);

27
fs/cifs/file.c
View File

@ -759,10 +759,15 @@ cifs_del_lock_waiters(struct cifsLockInfo *lock)
}
}
#define CIFS_LOCK_OP 0
#define CIFS_READ_OP 1
#define CIFS_WRITE_OP 2
/* @rw_check : 0 - no op, 1 - read, 2 - write */
static bool
cifs_find_fid_lock_conflict(struct cifs_fid_locks *fdlocks, __u64 offset,
__u64 length, __u8 type, struct cifsFileInfo *cfile,
struct cifsLockInfo **conf_lock, bool rw_check)
struct cifsLockInfo **conf_lock, int rw_check)
{
struct cifsLockInfo *li;
struct cifsFileInfo *cur_cfile = fdlocks->cfile;
@ -772,9 +777,13 @@ cifs_find_fid_lock_conflict(struct cifs_fid_locks *fdlocks, __u64 offset,
if (offset + length <= li->offset ||
offset >= li->offset + li->length)
continue;
if (rw_check && server->ops->compare_fids(cfile, cur_cfile) &&
current->tgid == li->pid)
continue;
if (rw_check != CIFS_LOCK_OP && current->tgid == li->pid &&
server->ops->compare_fids(cfile, cur_cfile)) {
/* shared lock prevents write op through the same fid */
if (!(li->type & server->vals->shared_lock_type) ||
rw_check != CIFS_WRITE_OP)
continue;
}
if ((type & server->vals->shared_lock_type) &&
((server->ops->compare_fids(cfile, cur_cfile) &&
current->tgid == li->pid) || type == li->type))
@ -789,7 +798,7 @@ cifs_find_fid_lock_conflict(struct cifs_fid_locks *fdlocks, __u64 offset,
bool
cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset, __u64 length,
__u8 type, struct cifsLockInfo **conf_lock,
bool rw_check)
int rw_check)
{
bool rc = false;
struct cifs_fid_locks *cur;
@ -825,7 +834,7 @@ cifs_lock_test(struct cifsFileInfo *cfile, __u64 offset, __u64 length,
down_read(&cinode->lock_sem);
exist = cifs_find_lock_conflict(cfile, offset, length, type,
&conf_lock, false);
&conf_lock, CIFS_LOCK_OP);
if (exist) {
flock->fl_start = conf_lock->offset;
flock->fl_end = conf_lock->offset + conf_lock->length - 1;
@ -872,7 +881,7 @@ try_again:
down_write(&cinode->lock_sem);
exist = cifs_find_lock_conflict(cfile, lock->offset, lock->length,
lock->type, &conf_lock, false);
lock->type, &conf_lock, CIFS_LOCK_OP);
if (!exist && cinode->can_cache_brlcks) {
list_add_tail(&lock->llist, &cfile->llist->locks);
up_write(&cinode->lock_sem);
@ -2466,7 +2475,7 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov,
down_read(&cinode->lock_sem);
if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs),
server->vals->exclusive_lock_type, NULL,
true)) {
CIFS_WRITE_OP)) {
mutex_lock(&inode->i_mutex);
rc = __generic_file_aio_write(iocb, iov, nr_segs,
&iocb->ki_pos);
@ -2901,7 +2910,7 @@ cifs_strict_readv(struct kiocb *iocb, const struct iovec *iov,
down_read(&cinode->lock_sem);
if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs),
tcon->ses->server->vals->shared_lock_type,
NULL, true))
NULL, CIFS_READ_OP))
rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
up_read(&cinode->lock_sem);
return rc;