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>
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index fdf3032..6f77abd 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -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 @@
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 @@
.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 @@
.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,
};