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CIFS: Check for mandatory brlocks on read/write
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Currently CIFS code accept read/write ops on mandatory locked area
when two processes use the same file descriptor - it's wrong.
Fix this by serializing io and brlock operations on the inode.

Signed-off-by: Pavel Shilovsky <pshilovsky@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>
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Pavel Shilovsky authored and Steve French committed Sep 25, 2012
1 parent 1b4b55a commit 579f905
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Showing 2 changed files with 102 additions and 23 deletions.
4 changes: 4 additions & 0 deletions fs/cifs/cifsproto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,10 @@ extern struct smb_vol *cifs_get_volume_info(char *mount_data,
extern int cifs_mount(struct cifs_sb_info *, struct smb_vol *);
extern void cifs_umount(struct cifs_sb_info *);
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);

#if IS_ENABLED(CONFIG_CIFS_DFS_UPCALL)
extern void cifs_dfs_release_automount_timer(void);
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121 changes: 98 additions & 23 deletions fs/cifs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -707,7 +707,7 @@ cifs_del_lock_waiters(struct cifsLockInfo *lock)
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)
struct cifsLockInfo **conf_lock, bool rw_check)
{
struct cifsLockInfo *li;
struct cifsFileInfo *cur_cfile = fdlocks->cfile;
Expand All @@ -717,27 +717,32 @@ 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 ((type & server->vals->shared_lock_type) &&
((server->ops->compare_fids(cfile, cur_cfile) &&
current->tgid == li->pid) || type == li->type))
continue;
*conf_lock = li;
if (conf_lock)
*conf_lock = li;
return true;
}
return false;
}

static bool
bool
cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset, __u64 length,
__u8 type, struct cifsLockInfo **conf_lock)
__u8 type, struct cifsLockInfo **conf_lock,
bool rw_check)
{
bool rc = false;
struct cifs_fid_locks *cur;
struct cifsInodeInfo *cinode = CIFS_I(cfile->dentry->d_inode);

list_for_each_entry(cur, &cinode->llist, llist) {
rc = cifs_find_fid_lock_conflict(cur, offset, length, type,
cfile, conf_lock);
cfile, conf_lock, rw_check);
if (rc)
break;
}
Expand Down Expand Up @@ -765,7 +770,7 @@ 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);
&conf_lock, false);
if (exist) {
flock->fl_start = conf_lock->offset;
flock->fl_end = conf_lock->offset + conf_lock->length - 1;
Expand Down Expand Up @@ -812,7 +817,7 @@ 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);
lock->type, &conf_lock, false);
if (!exist && cinode->can_cache_brlcks) {
list_add_tail(&lock->llist, &cfile->llist->locks);
up_write(&cinode->lock_sem);
Expand Down Expand Up @@ -2394,15 +2399,58 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov,
return written;
}

ssize_t cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
static ssize_t
cifs_writev(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct inode *inode;
struct file *file = iocb->ki_filp;
struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
struct inode *inode = file->f_mapping->host;
struct cifsInodeInfo *cinode = CIFS_I(inode);
struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
ssize_t rc = -EACCES;

inode = iocb->ki_filp->f_path.dentry->d_inode;
BUG_ON(iocb->ki_pos != pos);

if (CIFS_I(inode)->clientCanCacheAll)
return generic_file_aio_write(iocb, iov, nr_segs, pos);
sb_start_write(inode->i_sb);

/*
* We need to hold the sem to be sure nobody modifies lock list
* with a brlock that prevents writing.
*/
down_read(&cinode->lock_sem);
if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs),
server->vals->exclusive_lock_type, NULL,
true)) {
mutex_lock(&inode->i_mutex);
rc = __generic_file_aio_write(iocb, iov, nr_segs,
&iocb->ki_pos);
mutex_unlock(&inode->i_mutex);
}

if (rc > 0 || rc == -EIOCBQUEUED) {
ssize_t err;

err = generic_write_sync(file, pos, rc);
if (err < 0 && rc > 0)
rc = err;
}

up_read(&cinode->lock_sem);
sb_end_write(inode->i_sb);
return rc;
}

ssize_t
cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
struct cifsInodeInfo *cinode = CIFS_I(inode);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifsFileInfo *cfile = (struct cifsFileInfo *)
iocb->ki_filp->private_data;
struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);

/*
* In strict cache mode we need to write the data to the server exactly
Expand All @@ -2411,7 +2459,15 @@ ssize_t cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
* not on the region from pos to ppos+len-1.
*/

return cifs_user_writev(iocb, iov, nr_segs, pos);
if (!cinode->clientCanCacheAll)
return cifs_user_writev(iocb, iov, nr_segs, pos);

if (cap_unix(tcon->ses) &&
(CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
return generic_file_aio_write(iocb, iov, nr_segs, pos);

return cifs_writev(iocb, iov, nr_segs, pos);
}

static struct cifs_readdata *
Expand Down Expand Up @@ -2746,15 +2802,17 @@ ssize_t cifs_user_readv(struct kiocb *iocb, const struct iovec *iov,
return read;
}

ssize_t cifs_strict_readv(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
ssize_t
cifs_strict_readv(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct inode *inode;

inode = iocb->ki_filp->f_path.dentry->d_inode;

if (CIFS_I(inode)->clientCanCacheRead)
return generic_file_aio_read(iocb, iov, nr_segs, pos);
struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
struct cifsInodeInfo *cinode = CIFS_I(inode);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifsFileInfo *cfile = (struct cifsFileInfo *)
iocb->ki_filp->private_data;
struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
int rc = -EACCES;

/*
* In strict cache mode we need to read from the server all the time
Expand All @@ -2764,8 +2822,25 @@ ssize_t cifs_strict_readv(struct kiocb *iocb, const struct iovec *iov,
* on pages affected by this read but not on the region from pos to
* pos+len-1.
*/
if (!cinode->clientCanCacheRead)
return cifs_user_readv(iocb, iov, nr_segs, pos);

return cifs_user_readv(iocb, iov, nr_segs, pos);
if (cap_unix(tcon->ses) &&
(CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
return generic_file_aio_read(iocb, iov, nr_segs, pos);

/*
* We need to hold the sem to be sure nobody modifies lock list
* with a brlock that prevents reading.
*/
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))
rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
up_read(&cinode->lock_sem);
return rc;
}

static ssize_t
Expand Down

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