Commit 6dd47406 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Al Viro
Browse files

nilfs2: simplify remaining sget() use



This simplifies the test function passed on the remaining sget()
callsite in nilfs.

Instead of checking mount type (i.e. ro-mount/rw-mount/snapshot mount)
in the test function passed to sget(), this patch first looks up the
nilfs_sb_info struct which the given mount type matches, and then
acquires the super block instance holding the nilfs_sb_info.
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3f82ff55
......@@ -60,6 +60,7 @@ struct nilfs_sb_info {
struct super_block *s_super; /* reverse pointer to super_block */
struct the_nilfs *s_nilfs;
struct list_head s_list; /* list head for nilfs->ns_supers */
atomic_t s_count; /* reference count */
/* Segment constructor */
struct list_head s_dirty_files; /* dirty files list */
......
......@@ -336,7 +336,7 @@ static void nilfs_put_super(struct super_block *sb)
put_nilfs(sbi->s_nilfs);
sbi->s_super = NULL;
sb->s_fs_info = NULL;
kfree(sbi);
nilfs_put_sbinfo(sbi);
unlock_kernel();
}
......@@ -785,6 +785,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
get_nilfs(nilfs);
sbi->s_nilfs = nilfs;
sbi->s_super = sb;
atomic_set(&sbi->s_count, 1);
err = init_nilfs(nilfs, sbi, (char *)data);
if (err)
......@@ -902,7 +903,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
failed_sbi:
put_nilfs(nilfs);
sb->s_fs_info = NULL;
kfree(sbi);
nilfs_put_sbinfo(sbi);
return err;
}
......@@ -1014,6 +1015,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
struct nilfs_super_data {
struct block_device *bdev;
struct nilfs_sb_info *sbi;
__u64 cno;
int flags;
};
......@@ -1071,27 +1073,8 @@ static int nilfs_set_bdev_super(struct super_block *s, void *data)
static int nilfs_test_bdev_super(struct super_block *s, void *data)
{
struct nilfs_super_data *sd = data;
int ret;
if (s->s_bdev != sd->bdev)
return 0;
if (!((s->s_flags | sd->flags) & MS_RDONLY))
return 1; /* Reuse an old R/W-mode super_block */
if (s->s_flags & sd->flags & MS_RDONLY) {
if (down_read_trylock(&s->s_umount)) {
ret = s->s_root &&
(sd->cno == NILFS_SB(s)->s_snapshot_cno);
up_read(&s->s_umount);
/*
* This path is locked with sb_lock by sget().
* So, drop_super() causes deadlock.
*/
return ret;
}
}
return 0;
return sd->sbi && s->s_fs_info == (void *)sd->sbi;
}
static int
......@@ -1112,7 +1095,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
* much more information than normal filesystems to identify mount
* instance. For snapshot mounts, not only a mount type (ro-mount
* or rw-mount) but also a checkpoint number is required.
* The results are passed in sget() using nilfs_super_data.
*/
sd.cno = 0;
sd.flags = flags;
......@@ -1148,13 +1130,23 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
}
/*
* Search specified snapshot or R/W mode super_block
* Find existing nilfs_sb_info struct
*/
sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);
if (!sd.cno)
/* trying to get the latest checkpoint. */
sd.cno = nilfs_last_cno(nilfs);
/*
* Get super block instance holding the nilfs_sb_info struct.
* A new instance is allocated if no existing mount is present or
* existing instance has been unmounted.
*/
s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);
if (sd.sbi)
nilfs_put_sbinfo(sd.sbi);
if (IS_ERR(s)) {
err = PTR_ERR(s);
goto failed_unlock;
......
......@@ -664,6 +664,56 @@ int nilfs_near_disk_full(struct the_nilfs *nilfs)
return ret;
}
/**
* nilfs_find_sbinfo - find existing nilfs_sb_info structure
* @nilfs: nilfs object
* @rw_mount: mount type (non-zero value for read/write mount)
* @cno: checkpoint number (zero for read-only mount)
*
* nilfs_find_sbinfo() returns the nilfs_sb_info structure which
* @rw_mount and @cno (in case of snapshots) matched. If no instance
* was found, NULL is returned. Although the super block instance can
* be unmounted after this function returns, the nilfs_sb_info struct
* is kept on memory until nilfs_put_sbinfo() is called.
*/
struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
int rw_mount, __u64 cno)
{
struct nilfs_sb_info *sbi;
down_read(&nilfs->ns_sem);
/*
* The SNAPSHOT flag and sb->s_flags are supposed to be
* protected with nilfs->ns_sem.
*/
sbi = nilfs->ns_current;
if (rw_mount) {
if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
goto found; /* read/write mount */
else
goto out;
} else if (cno == 0) {
if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
goto found; /* read-only mount */
else
goto out;
}
list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
if (nilfs_test_opt(sbi, SNAPSHOT) &&
sbi->s_snapshot_cno == cno)
goto found; /* snapshot mount */
}
out:
up_read(&nilfs->ns_sem);
return NULL;
found:
atomic_inc(&sbi->s_count);
up_read(&nilfs->ns_sem);
return sbi;
}
int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
int snapshot_mount)
{
......
......@@ -201,6 +201,7 @@ void put_nilfs(struct the_nilfs *);
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 *);
struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
int nilfs_near_disk_full(struct the_nilfs *);
void nilfs_fall_back_super_block(struct the_nilfs *);
......@@ -243,6 +244,12 @@ nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
mutex_unlock(&nilfs->ns_writer_mutex);
}
static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
{
if (!atomic_dec_and_test(&sbi->s_count))
kfree(sbi);
}
static inline void
nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
sector_t *seg_start, sector_t *seg_end)
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment