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Date: Fri, 15 May 2009 15:37:26 +0900
From: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To: Al Viro <viro@...iv.linux.org.uk>,
Christoph Hellwig <hch@...radead.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
Christoph Hellwig <hch@...radead.org>,
Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 4/4] nilfs2: reduce bd_mount_sem use to a minimum
This will get rid of bd_mount_sem use from nilfs except ones
surrounding an sget() call.
The intended exclusion control is replaced by ns_mount_mutex that
this patch inserts in the nilfs object.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
---
fs/nilfs2/cpfile.c | 6 +++---
fs/nilfs2/super.c | 20 +++++++++++---------
fs/nilfs2/the_nilfs.c | 1 +
fs/nilfs2/the_nilfs.h | 2 ++
4 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index e90b60d..79346a5 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -862,11 +862,11 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
case NILFS_CHECKPOINT:
/*
* Check for protecting existing snapshot mounts:
- * bd_mount_sem is used to make this operation atomic and
+ * ns_mount_sem is used to make this operation atomic and
* exclusive with a new mount job. Though it doesn't cover
* umount, it's enough for the purpose.
*/
- down(&nilfs->ns_bdev->bd_mount_sem);
+ mutex_lock(&nilfs->ns_mount_mutex);
if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
/* Current implementation does not have to protect
plain read-only mounts since they are exclusive
@@ -875,7 +875,7 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
ret = -EBUSY;
} else
ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
- up(&nilfs->ns_bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
return ret;
case NILFS_SNAPSHOT:
return nilfs_cpfile_set_snapshot(cpfile, cno);
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 5992997..64ef0b9 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -750,7 +750,7 @@ int nilfs_store_magic_and_option(struct super_block *sb,
* @silent: silent mode flag
* @nilfs: the_nilfs struct
*
- * This function is called exclusively by bd_mount_mutex.
+ * This function is called exclusively by nilfs->ns_mount_mutex.
* So, the recovery process is protected from other simultaneous mounts.
*/
static int
@@ -943,7 +943,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
* store the current valid flag. (It may have been changed
* by fsck since we originally mounted the partition.)
*/
- down(&sb->s_bdev->bd_mount_sem);
+ mutex_lock(&nilfs->ns_mount_mutex);
if (nilfs_current_mount_is_there(nilfs, 0, sbi)) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount because an RW-mount exists.\n",
@@ -971,13 +971,13 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
nilfs_setup_super(sbi);
up_write(&nilfs->ns_sem);
- up(&sb->s_bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
}
out:
return 0;
rw_remount_failed:
- up(&sb->s_bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
restore_opts:
sb->s_flags = old_sb_flags;
sbi->s_mount_opt = old_opts.mount_opt;
@@ -1100,7 +1100,7 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
goto failed;
}
- down(&sd.bdev->bd_mount_sem);
+ mutex_lock(&nilfs->ns_mount_mutex);
if (!sd.cno &&
nilfs_current_mount_is_there(nilfs, !(flags & MS_RDONLY), NULL)) {
@@ -1115,7 +1115,9 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
/* trying to get the latest checkpoint. */
sd.cno = nilfs_last_cno(nilfs);
+ down(&sd.bdev->bd_mount_sem);
s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);
+ up(&sd.bdev->bd_mount_sem);
if (IS_ERR(s)) {
err = PTR_ERR(s);
goto failed_unlock;
@@ -1137,7 +1139,7 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
need_to_close = 0;
}
- up(&sd.bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
put_nilfs(nilfs);
if (need_to_close)
close_bdev_exclusive(sd.bdev, flags);
@@ -1145,7 +1147,7 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
return 0;
failed_unlock:
- up(&sd.bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
put_nilfs(nilfs);
failed:
close_bdev_exclusive(sd.bdev, flags);
@@ -1154,14 +1156,14 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
cancel_new:
/* Abandoning the newly allocated superblock */
- up(&sd.bdev->bd_mount_sem);
+ mutex_unlock(&nilfs->ns_mount_mutex);
put_nilfs(nilfs);
up_write(&s->s_umount);
deactivate_super(s);
/*
* deactivate_super() invokes close_bdev_exclusive().
* We must finish all post-cleaning before this call;
- * put_nilfs() and unlocking bd_mount_sem need the block device.
+ * put_nilfs() needs the block device.
*/
return err;
}
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 8ac22f6..51ffde0 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -72,6 +72,7 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
atomic_set(&nilfs->ns_writer_refcount, -1);
atomic_set(&nilfs->ns_ndirtyblks, 0);
init_rwsem(&nilfs->ns_sem);
+ mutex_init(&nilfs->ns_mount_mutex);
mutex_init(&nilfs->ns_writer_mutex);
INIT_LIST_HEAD(&nilfs->ns_list);
INIT_LIST_HEAD(&nilfs->ns_supers);
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 4249eb3..76af4c9 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -48,6 +48,7 @@ enum {
* @ns_bdi: backing dev info
* @ns_writer: back pointer to writable nilfs_sb_info
* @ns_sem: semaphore for shared states
+ * @ns_mount_mutex: mutex protecting mount/remount process of nilfs
* @ns_writer_mutex: mutex protecting ns_writer attach/detach
* @ns_writer_refcount: number of referrers on ns_writer
* @ns_sbh: buffer heads of on-disk super blocks
@@ -95,6 +96,7 @@ struct the_nilfs {
struct backing_dev_info *ns_bdi;
struct nilfs_sb_info *ns_writer;
struct rw_semaphore ns_sem;
+ struct mutex ns_mount_mutex;
struct mutex ns_writer_mutex;
atomic_t ns_writer_refcount;
--
1.6.2
--
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