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authorM. Mohan Kumar <mohan@in.ibm.com>2010-09-27 11:34:24 +0530
committerEric Van Hensbergen <ericvh@gmail.com>2010-10-28 09:08:47 -0500
commita099027c779068b834f335cfdc3f2bf10f531dd9 (patch)
treeeee43443cce85a03c13b1cfdd25bf451445cf78f /fs/9p
parent920e65dc6911da28a58e17f4b683302636fc6d8e (diff)
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>
Diffstat (limited to 'fs/9p')
-rw-r--r--fs/9p/v9fs_vfs.h2
-rw-r--r--fs/9p/vfs_file.c160
2 files changed, 160 insertions, 2 deletions
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 09861295eef..d26db1932f7 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -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)
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index fdf303207c7..6f77abd2318 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 @@ 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,
};