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Commit 081c0414 authored by Pavel Shilovsky's avatar Pavel Shilovsky Committed by Steve French
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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: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent eb1b3fa5

fs/cifs/cifsproto.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

fs/cifs/file.c

+18 −9
Original line number Diff line number Diff line
@@ -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)

		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 @@ cifs_lock_add_if(struct cifsFileInfo *cfile, struct cifsLockInfo *lock, 
	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;