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nfs: introduce mount option '-olocal_lock' to make locks local
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NFS clients since 2.6.12 support flock locks by emulating fcntl byte-range
locks. Due to this, some windows applications which seem to use both flock
(share mode lock mapped as flock by Samba) and fcntl locks sequentially on
the same file, can't lock as they falsely assume the file is already locked.
The problem was reported on a setup with windows clients accessing excel files
on a Samba exported share which is originally a NFS mount from a NetApp filer.

Older NFS clients (< 2.6.12) did not see this problem as flock locks were
considered local. To support legacy flock behavior, this patch adds a mount
option "-olocal_lock=" which can take the following values:

   'none'  		- Neither flock locks nor POSIX locks are local
   'flock' 		- flock locks are local
   'posix' 		- fcntl/POSIX locks are local
   'all'		- Both flock locks and POSIX locks are local

Testing:

   - This patch was tested by using -olocal_lock option with different values
     and the NLM calls were noted from the network packet captured.

     'none'  - NLM calls were seen during both flock() and fcntl(), flock lock
   	       was granted, fcntl was denied
     'flock' - no NLM calls for flock(), NLM call was seen for fcntl(),
   	       granted
     'posix' - NLM call was seen for flock() - granted, no NLM call for fcntl()
     'all'   - no NLM calls were seen during both flock() and fcntl()

   - No bugs were seen during NFSv4 locking/unlocking in general and NFSv4
     reboot recovery.

Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Suresh Jayaraman authored and Trond Myklebust committed Sep 23, 2010
1 parent 6318594 commit 5eebde2
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Showing 4 changed files with 97 additions and 16 deletions.
6 changes: 4 additions & 2 deletions fs/nfs/client.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -635,7 +635,8 @@ static int nfs_create_rpc_client(struct nfs_client *clp,
*/
static void nfs_destroy_server(struct nfs_server *server)
{
if (!(server->flags & NFS_MOUNT_NONLM))
if (!(server->flags & NFS_MOUNT_LOCAL_FLOCK) ||
!(server->flags & NFS_MOUNT_LOCAL_FCNTL))
nlmclnt_done(server->nlm_host);
}

Expand All @@ -657,7 +658,8 @@ static int nfs_start_lockd(struct nfs_server *server)

if (nlm_init.nfs_version > 3)
return 0;
if (server->flags & NFS_MOUNT_NONLM)
if ((server->flags & NFS_MOUNT_LOCAL_FLOCK) &&
(server->flags & NFS_MOUNT_LOCAL_FCNTL))
return 0;

switch (clp->cl_proto) {
Expand Down
45 changes: 32 additions & 13 deletions fs/nfs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -684,7 +684,8 @@ static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
return ret;
}

static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
static int
do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
struct inode *inode = filp->f_mapping->host;
int status = 0;
Expand All @@ -699,7 +700,7 @@ static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
if (nfs_have_delegation(inode, FMODE_READ))
goto out_noconflict;

if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)
if (is_local)
goto out_noconflict;

status = NFS_PROTO(inode)->lock(filp, cmd, fl);
Expand Down Expand Up @@ -730,7 +731,8 @@ static int do_vfs_lock(struct file *file, struct file_lock *fl)
return res;
}

static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
static int
do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
struct inode *inode = filp->f_mapping->host;
int status;
Expand All @@ -745,15 +747,19 @@ static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
* If we're signalled while cleaning up locks on process exit, we
* still need to complete the unlock.
*/
/* Use local locking if mounted with "-onolock" */
if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
/*
* Use local locking if mounted with "-onolock" or with appropriate
* "-olocal_lock="
*/
if (!is_local)
status = NFS_PROTO(inode)->lock(filp, cmd, fl);
else
status = do_vfs_lock(filp, fl);
return status;
}

static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
static int
do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
struct inode *inode = filp->f_mapping->host;
int status;
Expand All @@ -766,8 +772,11 @@ static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
if (status != 0)
goto out;

/* Use local locking if mounted with "-onolock" */
if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
/*
* Use local locking if mounted with "-onolock" or with appropriate
* "-olocal_lock="
*/
if (!is_local)
status = NFS_PROTO(inode)->lock(filp, cmd, fl);
else
status = do_vfs_lock(filp, fl);
Expand All @@ -791,6 +800,7 @@ static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode *inode = filp->f_mapping->host;
int ret = -ENOLCK;
int is_local = 0;

dprintk("NFS: lock(%s/%s, t=%x, fl=%x, r=%lld:%lld)\n",
filp->f_path.dentry->d_parent->d_name.name,
Expand All @@ -804,18 +814,21 @@ static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
goto out_err;

if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
is_local = 1;

if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
ret = NFS_PROTO(inode)->lock_check_bounds(fl);
if (ret < 0)
goto out_err;
}

if (IS_GETLK(cmd))
ret = do_getlk(filp, cmd, fl);
ret = do_getlk(filp, cmd, fl, is_local);
else if (fl->fl_type == F_UNLCK)
ret = do_unlk(filp, cmd, fl);
ret = do_unlk(filp, cmd, fl, is_local);
else
ret = do_setlk(filp, cmd, fl);
ret = do_setlk(filp, cmd, fl, is_local);
out_err:
return ret;
}
Expand All @@ -825,6 +838,9 @@ static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
*/
static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode *inode = filp->f_mapping->host;
int is_local = 0;

dprintk("NFS: flock(%s/%s, t=%x, fl=%x)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name,
Expand All @@ -833,14 +849,17 @@ static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;

if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
is_local = 1;

/* We're simulating flock() locks using posix locks on the server */
fl->fl_owner = (fl_owner_t)filp;
fl->fl_start = 0;
fl->fl_end = OFFSET_MAX;

if (fl->fl_type == F_UNLCK)
return do_unlk(filp, cmd, fl);
return do_setlk(filp, cmd, fl);
return do_unlk(filp, cmd, fl, is_local);
return do_setlk(filp, cmd, fl, is_local);
}

/*
Expand Down
59 changes: 58 additions & 1 deletion fs/nfs/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,7 @@ enum {
Opt_addr, Opt_mountaddr, Opt_clientaddr,
Opt_lookupcache,
Opt_fscache_uniq,
Opt_local_lock,

/* Special mount options */
Opt_userspace, Opt_deprecated, Opt_sloppy,
Expand Down Expand Up @@ -171,6 +172,7 @@ static const match_table_t nfs_mount_option_tokens = {

{ Opt_lookupcache, "lookupcache=%s" },
{ Opt_fscache_uniq, "fsc=%s" },
{ Opt_local_lock, "local_lock=%s" },

{ Opt_err, NULL }
};
Expand Down Expand Up @@ -236,6 +238,22 @@ static match_table_t nfs_lookupcache_tokens = {
{ Opt_lookupcache_err, NULL }
};

enum {
Opt_local_lock_all, Opt_local_lock_flock, Opt_local_lock_posix,
Opt_local_lock_none,

Opt_local_lock_err
};

static match_table_t nfs_local_lock_tokens = {
{ Opt_local_lock_all, "all" },
{ Opt_local_lock_flock, "flock" },
{ Opt_local_lock_posix, "posix" },
{ Opt_local_lock_none, "none" },

{ Opt_local_lock_err, NULL }
};


static void nfs_umount_begin(struct super_block *);
static int nfs_statfs(struct dentry *, struct kstatfs *);
Expand Down Expand Up @@ -1009,9 +1027,13 @@ static int nfs_parse_mount_options(char *raw,
break;
case Opt_lock:
mnt->flags &= ~NFS_MOUNT_NONLM;
mnt->flags &= ~(NFS_MOUNT_LOCAL_FLOCK |
NFS_MOUNT_LOCAL_FCNTL);
break;
case Opt_nolock:
mnt->flags |= NFS_MOUNT_NONLM;
mnt->flags |= (NFS_MOUNT_LOCAL_FLOCK |
NFS_MOUNT_LOCAL_FCNTL);
break;
case Opt_v2:
mnt->flags &= ~NFS_MOUNT_VER3;
Expand Down Expand Up @@ -1412,6 +1434,34 @@ static int nfs_parse_mount_options(char *raw,
mnt->fscache_uniq = string;
mnt->options |= NFS_OPTION_FSCACHE;
break;
case Opt_local_lock:
string = match_strdup(args);
if (string == NULL)
goto out_nomem;
token = match_token(string, nfs_local_lock_tokens,
args);
kfree(string);
switch (token) {
case Opt_local_lock_all:
mnt->flags |= (NFS_MOUNT_LOCAL_FLOCK |
NFS_MOUNT_LOCAL_FCNTL);
break;
case Opt_local_lock_flock:
mnt->flags |= NFS_MOUNT_LOCAL_FLOCK;
break;
case Opt_local_lock_posix:
mnt->flags |= NFS_MOUNT_LOCAL_FCNTL;
break;
case Opt_local_lock_none:
mnt->flags &= ~(NFS_MOUNT_LOCAL_FLOCK |
NFS_MOUNT_LOCAL_FCNTL);
break;
default:
dfprintk(MOUNT, "NFS: invalid "
"local_lock argument\n");
return 0;
};
break;

/*
* Special options
Expand Down Expand Up @@ -1817,6 +1867,12 @@ static int nfs_validate_mount_data(void *options,
if (!args->nfs_server.hostname)
goto out_nomem;

if (!(data->flags & NFS_MOUNT_NONLM))
args->flags &= ~(NFS_MOUNT_LOCAL_FLOCK|
NFS_MOUNT_LOCAL_FCNTL);
else
args->flags |= (NFS_MOUNT_LOCAL_FLOCK|
NFS_MOUNT_LOCAL_FCNTL);
/*
* The legacy version 6 binary mount data from userspace has a
* field used only to transport selinux information into the
Expand Down Expand Up @@ -2433,7 +2489,8 @@ static void nfs4_fill_super(struct super_block *sb)

static void nfs4_validate_mount_flags(struct nfs_parsed_mount_data *args)
{
args->flags &= ~(NFS_MOUNT_NONLM|NFS_MOUNT_NOACL|NFS_MOUNT_VER3);
args->flags &= ~(NFS_MOUNT_NONLM|NFS_MOUNT_NOACL|NFS_MOUNT_VER3|
NFS_MOUNT_LOCAL_FLOCK|NFS_MOUNT_LOCAL_FCNTL);
}

static int nfs4_validate_text_mount_data(void *options,
Expand Down
3 changes: 3 additions & 0 deletions include/linux/nfs_mount.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,4 +71,7 @@ struct nfs_mount_data {
#define NFS_MOUNT_NORESVPORT 0x40000
#define NFS_MOUNT_LEGACY_INTERFACE 0x80000

#define NFS_MOUNT_LOCAL_FLOCK 0x100000
#define NFS_MOUNT_LOCAL_FCNTL 0x200000

#endif

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