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9p: Implement TLOCK 

Synopsis

    size[4] TLock tag[2] fid[4] flock[n]
    size[4] RLock tag[2] status[1]

Description

Tlock is used to acquire/release byte range posix locks on a file
identified by given fid. The reply contains status of the lock request

    flock structure:
        type[1] - Type of lock: F_RDLCK, F_WRLCK, F_UNLCK
        flags[4] - Flags could be either of
          P9_LOCK_FLAGS_BLOCK - Blocked lock request, if there is a
            conflicting lock exists, wait for that lock to be released.
          P9_LOCK_FLAGS_RECLAIM - Reclaim lock request, used when client is
            trying to reclaim a lock after a server restrart (due to crash)
        start[8] - Starting offset for lock
        length[8] - Number of bytes to lock
          If length is 0, lock all bytes starting at the location 'start'
          through to the end of file
        pid[4] - PID of the process that wants to take lock
        client_id[4] - Unique client id

        status[1] - Status of the lock request, can be
          P9_LOCK_SUCCESS(0), P9_LOCK_BLOCKED(1), P9_LOCK_ERROR(2) or
          P9_LOCK_GRACE(3)
          P9_LOCK_SUCCESS - Request was successful
          P9_LOCK_BLOCKED - A conflicting lock is held by another process
          P9_LOCK_ERROR - Error while processing the lock request
          P9_LOCK_GRACE - Server is in grace period, it can't accept new lock
            requests in this period (except locks with
            P9_LOCK_FLAGS_RECLAIM flag set)

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
M. Mohan Kumar 2010-09-27 11:34:24 +05:30 committed by Eric Van Hensbergen
parent 920e65dc69
commit a099027c77
5 changed files with 222 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/9p/v9fs_vfs.h
View File

@ -65,3 +65,5 @@ int v9fs_uflags2omode(int uflags, int extended);
ssize_t v9fs_file_readn(struct file *, char *, char __user *, u32, u64);
void v9fs_blank_wstat(struct p9_wstat *wstat);
int v9fs_vfs_setattr_dotl(struct dentry *, struct iattr *);
#define P9_LOCK_TIMEOUT (30*HZ)

160
fs/9p/vfs_file.c
View File

@ -33,6 +33,7 @@
#include <linux/inet.h>
#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/utsname.h>
#include <asm/uaccess.h>
#include <linux/idr.h>
#include <net/9p/9p.h>
@ -133,6 +134,159 @@ static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
return res;
}
static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
{
struct p9_flock flock;
struct p9_fid *fid;
uint8_t status;
int res = 0;
unsigned char fl_type;
fid = filp->private_data;
BUG_ON(fid == NULL);
if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
BUG();
res = posix_lock_file_wait(filp, fl);
if (res < 0)
goto out;
/* convert posix lock to p9 tlock args */
memset(&flock, 0, sizeof(flock));
flock.type = fl->fl_type;
flock.start = fl->fl_start;
if (fl->fl_end == OFFSET_MAX)
flock.length = 0;
else
flock.length = fl->fl_end - fl->fl_start + 1;
flock.proc_id = fl->fl_pid;
flock.client_id = utsname()->nodename;
if (IS_SETLKW(cmd))
flock.flags = P9_LOCK_FLAGS_BLOCK;
/*
* if its a blocked request and we get P9_LOCK_BLOCKED as the status
* for lock request, keep on trying
*/
for (;;) {
res = p9_client_lock_dotl(fid, &flock, &status);
if (res < 0)
break;
if (status != P9_LOCK_BLOCKED)
break;
if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
break;
schedule_timeout_interruptible(P9_LOCK_TIMEOUT);
}
/* map 9p status to VFS status */
switch (status) {
case P9_LOCK_SUCCESS:
res = 0;
break;
case P9_LOCK_BLOCKED:
res = -EAGAIN;
break;
case P9_LOCK_ERROR:
case P9_LOCK_GRACE:
res = -ENOLCK;
break;
default:
BUG();
}
/*
* incase server returned error for lock request, revert
* it locally
*/
if (res < 0 && fl->fl_type != F_UNLCK) {
fl_type = fl->fl_type;
fl->fl_type = F_UNLCK;
res = posix_lock_file_wait(filp, fl);
fl->fl_type = fl_type;
}
out:
return res;
}
/**
* v9fs_file_lock_dotl - lock a file (or directory)
* @filp: file to be locked
* @cmd: lock command
* @fl: file lock structure
*
*/
static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode *inode = filp->f_path.dentry->d_inode;
int ret = -ENOLCK;
P9_DPRINTK(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n", filp,
cmd, fl, filp->f_path.dentry->d_name.name);
/* No mandatory locks */
if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
goto out_err;
if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
filemap_write_and_wait(inode->i_mapping);
invalidate_mapping_pages(&inode->i_data, 0, -1);
}
if (IS_SETLK(cmd) || IS_SETLKW(cmd))
ret = v9fs_file_do_lock(filp, cmd, fl);
else
ret = -EINVAL;
out_err:
return ret;
}
/**
* v9fs_file_flock_dotl - lock a file
* @filp: file to be locked
* @cmd: lock command
* @fl: file lock structure
*
*/
static int v9fs_file_flock_dotl(struct file *filp, int cmd,
struct file_lock *fl)
{
struct inode *inode = filp->f_path.dentry->d_inode;
int ret = -ENOLCK;
P9_DPRINTK(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %s\n", filp,
cmd, fl, filp->f_path.dentry->d_name.name);
/* No mandatory locks */
if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
goto out_err;
if (!(fl->fl_flags & FL_FLOCK))
goto out_err;
if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
filemap_write_and_wait(inode->i_mapping);
invalidate_mapping_pages(&inode->i_data, 0, -1);
}
/* Convert flock to posix lock */
fl->fl_owner = (fl_owner_t)filp;
fl->fl_start = 0;
fl->fl_end = OFFSET_MAX;
fl->fl_flags |= FL_POSIX;
fl->fl_flags ^= FL_FLOCK;
if (IS_SETLK(cmd) | IS_SETLKW(cmd))
ret = v9fs_file_do_lock(filp, cmd, fl);
else
ret = -EINVAL;
out_err:
return ret;
}
/**
* v9fs_file_readn - read from a file
* @filp: file pointer to read
@ -323,7 +477,8 @@ static const struct file_operations v9fs_cached_file_operations_dotl = {
.write = v9fs_file_write,
.open = v9fs_file_open,
.release = v9fs_dir_release,
.lock = v9fs_file_lock,
.lock = v9fs_file_lock_dotl,
.flock = v9fs_file_flock_dotl,
.mmap = generic_file_readonly_mmap,
.fsync = v9fs_file_fsync_dotl,
};
@ -345,7 +500,8 @@ const struct file_operations v9fs_file_operations_dotl = {
.write = v9fs_file_write,
.open = v9fs_file_open,
.release = v9fs_dir_release,
.lock = v9fs_file_lock,
.lock = v9fs_file_lock_dotl,
.flock = v9fs_file_flock_dotl,
.mmap = generic_file_readonly_mmap,
.fsync = v9fs_file_fsync_dotl,
};

28
include/net/9p/9p.h
View File

@ -165,6 +165,8 @@ enum p9_msg_t {
P9_RREADDIR,
P9_TFSYNC = 50,
P9_RFSYNC,
P9_TLOCK = 52,
P9_RLOCK,
P9_TLINK = 70,
P9_RLINK,
P9_TMKDIR = 72,
@ -464,6 +466,32 @@ struct p9_iattr_dotl {
u64 mtime_nsec;
};
#define P9_LOCK_SUCCESS 0
#define P9_LOCK_BLOCKED 1
#define P9_LOCK_ERROR 2
#define P9_LOCK_GRACE 3
#define P9_LOCK_FLAGS_BLOCK 1
#define P9_LOCK_FLAGS_RECLAIM 2
/* struct p9_flock: POSIX lock structure
* @type - type of lock
* @flags - lock flags
* @start - starting offset of the lock
* @length - number of bytes
* @proc_id - process id which wants to take lock
* @client_id - client id
*/
struct p9_flock {
u8 type;
u32 flags;
u64 start;
u64 length;
u32 proc_id;
char *client_id;
};
/* Structures for Protocol Operations */
struct p9_tstatfs {
u32 fid;

1
include/net/9p/client.h
View File

@ -249,6 +249,7 @@ int p9_client_mknod_dotl(struct p9_fid *oldfid, char *name, int mode,
dev_t rdev, gid_t gid, struct p9_qid *);
int p9_client_mkdir_dotl(struct p9_fid *fid, char *name, int mode,
gid_t gid, struct p9_qid *);
int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status);
struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
void p9_client_cb(struct p9_client *c, struct p9_req_t *req);

33
net/9p/client.c
View File

@ -1803,3 +1803,36 @@ error:
}
EXPORT_SYMBOL(p9_client_mkdir_dotl);
int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status)
{
int err;
struct p9_client *clnt;
struct p9_req_t *req;
err = 0;
clnt = fid->clnt;
P9_DPRINTK(P9_DEBUG_9P, ">>> TLOCK fid %d type %i flags %d "
"start %lld length %lld proc_id %d client_id %s\n",
fid->fid, flock->type, flock->flags, flock->start,
flock->length, flock->proc_id, flock->client_id);
req = p9_client_rpc(clnt, P9_TLOCK, "dbdqqds", fid->fid, flock->type,
flock->flags, flock->start, flock->length,
flock->proc_id, flock->client_id);
if (IS_ERR(req))
return PTR_ERR(req);
err = p9pdu_readf(req->rc, clnt->proto_version, "b", status);
if (err) {
p9pdu_dump(1, req->rc);
goto error;
}
P9_DPRINTK(P9_DEBUG_9P, "<<< RLOCK status %i\n", *status);
error:
p9_free_req(clnt, req);
return err;
}
EXPORT_SYMBOL(p9_client_lock_dotl);