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Message-Id: <1242369446-25771-3-git-send-email-konishi.ryusuke@lab.ntt.co.jp>
Date: Fri, 15 May 2009 15:37:24 +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>,
Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 2/4] nilfs2: stop using sget to check if current mount is there
This stops using sget() for checking if an r/w-mount or an r/o-mount
exists on the device. This elimination is achieved by scanning
existent nilfs->ns_supers list.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Cc: Al Viro <viro@...iv.linux.org.uk>
---
fs/nilfs2/super.c | 71 +++++++------------------------------------------
fs/nilfs2/the_nilfs.c | 35 ++++++++++++++++++++++++
fs/nilfs2/the_nilfs.h | 2 +
3 files changed, 47 insertions(+), 61 deletions(-)
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 8131615..afa67ec 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -66,8 +66,6 @@ MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
MODULE_LICENSE("GPL");
static int nilfs_remount(struct super_block *sb, int *flags, char *data);
-static int test_exclusive_mount(struct file_system_type *fs_type,
- struct block_device *bdev, int flags);
/**
* nilfs_error() - report failure condition on a filesystem
@@ -946,10 +944,9 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
* by fsck since we originally mounted the partition.)
*/
down(&sb->s_bdev->bd_mount_sem);
- /* Check existing RW-mount */
- if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {
+ if (nilfs_current_mount_is_there(nilfs, 0, sbi)) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
- "remount because a RW-mount exists.\n",
+ "remount because an RW-mount exists.\n",
sb->s_id);
err = -EBUSY;
goto rw_remount_failed;
@@ -1110,11 +1107,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
* while we are mounting
*/
down(&sd.bdev->bd_mount_sem);
- if (!sd.cno &&
- (err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {
- err = (err < 0) ? : -EBUSY;
- goto failed_unlock;
- }
/*
* Phase-1: search any existent instance and get the_nilfs
@@ -1139,6 +1131,14 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
get_nilfs(nilfs);
up_write(&s->s_umount);
+ if (!sd.cno &&
+ nilfs_current_mount_is_there(nilfs, !(flags & MS_RDONLY),
+ NULL)) {
+ err = -EBUSY;
+ deactivate_super(s);
+ put_nilfs(nilfs);
+ goto failed_unlock;
+ }
/*
* Phase-2: search specified snapshot or R/W mode super_block
*/
@@ -1210,57 +1210,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
return err;
}
-static int nilfs_test_bdev_super3(struct super_block *s, void *data)
-{
- struct nilfs_super_data *sd = data;
- int ret;
-
- if (s->s_bdev != sd->bdev)
- return 0;
- if (down_read_trylock(&s->s_umount)) {
- ret = (s->s_flags & MS_RDONLY) && s->s_root &&
- nilfs_test_opt(NILFS_SB(s), SNAPSHOT);
- up_read(&s->s_umount);
- if (ret)
- return 0; /* ignore snapshot mounts */
- }
- return !((sd->flags ^ s->s_flags) & MS_RDONLY);
-}
-
-static int __false_bdev_super(struct super_block *s, void *data)
-{
-#if 0 /* XXX: workaround for lock debug. This is not good idea */
- up_write(&s->s_umount);
-#endif
- return -EFAULT;
-}
-
-/**
- * test_exclusive_mount - check whether an exclusive RW/RO mount exists or not.
- * fs_type: filesystem type
- * bdev: block device
- * flag: 0 (check rw-mount) or MS_RDONLY (check ro-mount)
- * res: pointer to an integer to store result
- *
- * This function must be called within a section protected by bd_mount_mutex.
- */
-static int test_exclusive_mount(struct file_system_type *fs_type,
- struct block_device *bdev, int flags)
-{
- struct super_block *s;
- struct nilfs_super_data sd = { .flags = flags, .bdev = bdev };
-
- s = sget(fs_type, nilfs_test_bdev_super3, __false_bdev_super, &sd);
- if (IS_ERR(s)) {
- if (PTR_ERR(s) != -EFAULT)
- return PTR_ERR(s);
- return 0; /* Not found */
- }
- up_write(&s->s_umount);
- deactivate_super(s);
- return 1; /* Found */
-}
-
struct file_system_type nilfs_fs_type = {
.owner = THIS_MODULE,
.name = "nilfs2",
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 7f65b3b..e5599e1 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -639,3 +639,38 @@ int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
up_read(&nilfs->ns_sem);
return ret;
}
+
+/**
+ * nilfs_current_mount_is_there - check if a non-snapshot mount is there
+ * nilfs: nilfs object
+ * ro_mount: mount type (0: ro-mount, otherwise: r/w-mount)
+ * me: instance which should be excluded from the test
+ *
+ * nilfs_current_mount_is_there() returns a non-zero value if a
+ * current mount with the specified mount type exists. Otherwise zero
+ * is returned. The optional @me argument specifies the instance
+ * which should be excluded fronm this test. if NULL is specified to
+ * @me, this will check every instance.
+ */
+int nilfs_current_mount_is_there(struct the_nilfs *nilfs, int ro_mount,
+ struct nilfs_sb_info *me)
+{
+ struct nilfs_sb_info *sbi;
+ int found = 0;
+
+ down_read(&nilfs->ns_sem);
+ list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
+ /*
+ * The SNAPSHOT flag and sb->s_flags are supposed to be
+ * protected with nilfs->ns_sem.
+ */
+ if (nilfs_test_opt(sbi, SNAPSHOT) || sbi == me)
+ continue; /* exclude snapshot mounts and self */
+ if (!ro_mount == !(sbi->s_super->s_flags & MS_RDONLY)) {
+ found++;
+ break;
+ }
+ }
+ up_read(&nilfs->ns_sem);
+ return found;
+}
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 30fe587..e9cfd74 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -197,6 +197,8 @@ int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
+int nilfs_current_mount_is_there(struct the_nilfs *, int,
+ struct nilfs_sb_info *);
int nilfs_near_disk_full(struct the_nilfs *);
void nilfs_fall_back_super_block(struct the_nilfs *);
void nilfs_swap_super_block(struct the_nilfs *);
--
1.6.2
--
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