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ocfs2: POSIX file locks support 

This is actually pretty easy since fs/dlm already handles the bulk of the
work. The Ocfs2 userspace cluster stack module already uses fs/dlm as the
underlying lock manager, so I only had to add the right calls.

Cluster-aware POSIX locks ("plocks") can be turned off by the same means at
UNIX locks - mount with 'noflocks', or create a local-only Ocfs2 volume.
Internally, the file system uses two sets of file_operations, depending on
whether cluster aware plocks is required. This turns out to be easier than
implementing local-only versions of ->lock.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This commit is contained in:
Mark Fasheh 2008-07-21 14:29:16 -07:00
parent a447c09324
commit 53da4939f3
8 changed files with 155 additions and 3 deletions
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53
fs/ocfs2/file.c
View File

@ -2237,6 +2237,10 @@ const struct inode_operations ocfs2_special_file_iops = {
.permission = ocfs2_permission,
};
/*
* Other than ->lock, keep ocfs2_fops and ocfs2_dops in sync with
* ocfs2_fops_no_plocks and ocfs2_dops_no_plocks!
*/
const struct file_operations ocfs2_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@ -2250,13 +2254,60 @@ const struct file_operations ocfs2_fops = {
.unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ocfs2_compat_ioctl,
#endif
.lock = ocfs2_lock,
.flock = ocfs2_flock,
.splice_read = ocfs2_file_splice_read,
.splice_write = ocfs2_file_splice_write,
};
const struct file_operations ocfs2_dops = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = ocfs2_readdir,
.fsync = ocfs2_sync_file,
.release = ocfs2_dir_release,
.open = ocfs2_dir_open,
.unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ocfs2_compat_ioctl,
#endif
.lock = ocfs2_lock,
.flock = ocfs2_flock,
};
/*
* POSIX-lockless variants of our file_operations.
*
* These will be used if the underlying cluster stack does not support
* posix file locking, if the user passes the "localflocks" mount
* option, or if we have a local-only fs.
*
* ocfs2_flock is in here because all stacks handle UNIX file locks,
* so we still want it in the case of no stack support for
* plocks. Internally, it will do the right thing when asked to ignore
* the cluster.
*/
const struct file_operations ocfs2_fops_no_plocks = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.mmap = ocfs2_mmap,
.fsync = ocfs2_sync_file,
.release = ocfs2_file_release,
.open = ocfs2_file_open,
.aio_read = ocfs2_file_aio_read,
.aio_write = ocfs2_file_aio_write,
.unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ocfs2_compat_ioctl,
#endif
.flock = ocfs2_flock,
.splice_read = ocfs2_file_splice_read,
.splice_write = ocfs2_file_splice_write,
};
const struct file_operations ocfs2_dops = {
const struct file_operations ocfs2_dops_no_plocks = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = ocfs2_readdir,

2
fs/ocfs2/file.h
View File

@ -28,6 +28,8 @@
extern const struct file_operations ocfs2_fops;
extern const struct file_operations ocfs2_dops;
extern const struct file_operations ocfs2_fops_no_plocks;
extern const struct file_operations ocfs2_dops_no_plocks;
extern const struct inode_operations ocfs2_file_iops;
extern const struct inode_operations ocfs2_special_file_iops;
struct ocfs2_alloc_context;

15
fs/ocfs2/inode.c
View File

@ -219,6 +219,7 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
struct super_block *sb;
struct ocfs2_super *osb;
int status = -EINVAL;
int use_plocks = 1;
mlog_entry("(0x%p, size:%llu)\n", inode,
(unsigned long long)le64_to_cpu(fe->i_size));
@ -226,6 +227,10 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
sb = inode->i_sb;
osb = OCFS2_SB(sb);
if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
ocfs2_mount_local(osb) || !ocfs2_stack_supports_plocks())
use_plocks = 0;
/* this means that read_inode cannot create a superblock inode
* today. change if needed. */
if (!OCFS2_IS_VALID_DINODE(fe) ||
@ -295,13 +300,19 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
switch (inode->i_mode & S_IFMT) {
case S_IFREG:
inode->i_fop = &ocfs2_fops;
if (use_plocks)
inode->i_fop = &ocfs2_fops;
else
inode->i_fop = &ocfs2_fops_no_plocks;
inode->i_op = &ocfs2_file_iops;
i_size_write(inode, le64_to_cpu(fe->i_size));
break;
case S_IFDIR:
inode->i_op = &ocfs2_dir_iops;
inode->i_fop = &ocfs2_dops;
if (use_plocks)
inode->i_fop = &ocfs2_dops;
else
inode->i_fop = &ocfs2_dops_no_plocks;
i_size_write(inode, le64_to_cpu(fe->i_size));
break;
case S_IFLNK:

15
fs/ocfs2/locks.c
View File

@ -24,6 +24,7 @@
*/
#include <linux/fs.h>
#include <linux/fcntl.h>
#define MLOG_MASK_PREFIX ML_INODE
#include <cluster/masklog.h>
@ -32,6 +33,7 @@
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
#include "locks.h"
static int ocfs2_do_flock(struct file *file, struct inode *inode,
@ -123,3 +125,16 @@ int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
else
return ocfs2_do_flock(file, inode, cmd, fl);
}
int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl)
{
struct inode *inode = file->f_mapping->host;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
if (!(fl->fl_flags & FL_POSIX))
return -ENOLCK;
if (__mandatory_lock(inode))
return -ENOLCK;
return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl);
}

1
fs/ocfs2/locks.h
View File

@ -27,5 +27,6 @@
#define OCFS2_LOCKS_H
int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl);
int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl);
#endif /* OCFS2_LOCKS_H */

33
fs/ocfs2/stack_user.c
View File

@ -28,6 +28,7 @@
#include "ocfs2.h" /* For struct ocfs2_lock_res */
#include "stackglue.h"
#include <linux/dlm_plock.h>
/*
* The control protocol starts with a handshake. Until the handshake
@ -746,6 +747,37 @@ static void user_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
{
}
static int user_plock(struct ocfs2_cluster_connection *conn,
u64 ino,
struct file *file,
int cmd,
struct file_lock *fl)
{
/*
* This more or less just demuxes the plock request into any
* one of three dlm calls.
*
* Internally, fs/dlm will pass these to a misc device, which
* a userspace daemon will read and write to.
*
* For now, cancel requests (which happen internally only),
* are turned into unlocks. Most of this function taken from
* gfs2_lock.
*/
if (cmd == F_CANCELLK) {
cmd = F_SETLK;
fl->fl_type = F_UNLCK;
}
if (IS_GETLK(cmd))
return dlm_posix_get(conn->cc_lockspace, ino, file, fl);
else if (fl->fl_type == F_UNLCK)
return dlm_posix_unlock(conn->cc_lockspace, ino, file, fl);
else
return dlm_posix_lock(conn->cc_lockspace, ino, file, cmd, fl);
}
/*
* Compare a requested locking protocol version against the current one.
*
@ -839,6 +871,7 @@ static struct ocfs2_stack_operations ocfs2_user_plugin_ops = {
.dlm_unlock = user_dlm_unlock,
.lock_status = user_dlm_lock_status,
.lock_lvb = user_dlm_lvb,
.plock = user_plock,
.dump_lksb = user_dlm_dump_lksb,
};

20
fs/ocfs2/stackglue.c
View File

@ -288,6 +288,26 @@ void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
int ocfs2_stack_supports_plocks(void)
{
return !!(active_stack && active_stack->sp_ops->plock);
}
EXPORT_SYMBOL_GPL(ocfs2_stack_supports_plocks);
/*
* ocfs2_plock() can only be safely called if
* ocfs2_stack_supports_plocks() returned true
*/
int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
struct file *file, int cmd, struct file_lock *fl)
{
WARN_ON_ONCE(active_stack->sp_ops->plock == NULL);
if (active_stack->sp_ops->plock)
return active_stack->sp_ops->plock(conn, ino, file, cmd, fl);
return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(ocfs2_plock);
int ocfs2_cluster_connect(const char *stack_name,
const char *group,
int grouplen,

19
fs/ocfs2/stackglue.h
View File

@ -28,6 +28,10 @@
#include "dlm/dlmapi.h"
#include <linux/dlm.h>
/* Needed for plock-related prototypes */
struct file;
struct file_lock;
/*
* dlmconstants.h does not have a LOCAL flag. We hope to remove it
* some day, but right now we need it. Let's fake it. This value is larger
@ -186,6 +190,17 @@ struct ocfs2_stack_operations {
*/
void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
/*
* Cluster-aware posix locks
*
* This is NULL for stacks which do not support posix locks.
*/
int (*plock)(struct ocfs2_cluster_connection *conn,
u64 ino,
struct file *file,
int cmd,
struct file_lock *fl);
/*
* This is an optoinal debugging hook. If provided, the
* stack can dump debugging information about this lock.
@ -240,6 +255,10 @@ int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
int ocfs2_stack_supports_plocks(void);
int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
struct file *file, int cmd, struct file_lock *fl);
void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);