From 33c8e57c86d1bd1548c12a4f7c4bceb94b862cca Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 8 Jun 2009 01:39:29 +0900 Subject: nilfs2: get rid of sget use for acquiring nilfs object This will change the way to obtain nilfs object in nilfs_get_sb() function. Previously, a preliminary sget() call was performed, and the nilfs object was acquired from a super block instance found by the sget() call. This patch, instead, instroduces a new dedicated function find_or_create_nilfs(); as the name implies, the function finds an existent nilfs object from a global list or creates a new one if no object is found on the device. Signed-off-by: Ryusuke Konishi Cc: Al Viro Signed-off-by: Al Viro --- fs/nilfs2/the_nilfs.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/nilfs2/the_nilfs.h') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index 30fe58778d0..116caf96e7f 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -43,6 +43,7 @@ enum { * struct the_nilfs - struct to supervise multiple nilfs mount points * @ns_flags: flags * @ns_count: reference count + * @ns_list: list head for nilfs_list * @ns_bdev: block device * @ns_bdi: backing dev info * @ns_writer: back pointer to writable nilfs_sb_info @@ -88,6 +89,7 @@ enum { struct the_nilfs { unsigned long ns_flags; atomic_t ns_count; + struct list_head ns_list; struct block_device *ns_bdev; struct backing_dev_info *ns_bdi; @@ -191,7 +193,7 @@ THE_NILFS_FNS(DISCONTINUED, discontinued) #define NILFS_ALTSB_FREQ 60 /* spare superblock */ void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64); -struct the_nilfs *alloc_nilfs(struct block_device *); +struct the_nilfs *find_or_create_nilfs(struct block_device *); 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 *); -- cgit v1.2.3 From 3f82ff55168e92859119bf348e9e0bd6714d2fea Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 8 Jun 2009 01:39:30 +0900 Subject: nilfs2: get rid of sget use for checking if current mount is present This stops using sget() for checking if an r/w-mount or an r/o-mount exists on the device. This elimination uses a back pointer to the current mount added to nilfs object. Signed-off-by: Ryusuke Konishi Cc: Al Viro Signed-off-by: Al Viro --- fs/nilfs2/the_nilfs.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/nilfs2/the_nilfs.h') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index 116caf96e7f..99f7e29a533 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -50,6 +50,7 @@ enum { * @ns_sem: semaphore for shared states * @ns_writer_mutex: mutex protecting ns_writer attach/detach * @ns_writer_refcount: number of referrers on ns_writer + * @ns_current: back pointer to current mount * @ns_sbh: buffer heads of on-disk super blocks * @ns_sbp: pointers to super block data * @ns_sbwtime: previous write time of super blocks @@ -98,6 +99,8 @@ struct the_nilfs { struct mutex ns_writer_mutex; atomic_t ns_writer_refcount; + struct nilfs_sb_info *ns_current; + /* * used for * - loading the latest checkpoint exclusively. -- cgit v1.2.3 From 6dd4740662405a68bb229ac2b9e0aeaaf2188bf2 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 8 Jun 2009 01:39:31 +0900 Subject: 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: Ryusuke Konishi Cc: Al Viro Signed-off-by: Al Viro --- fs/nilfs2/the_nilfs.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/nilfs2/the_nilfs.h') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index 99f7e29a533..be4c040fd62 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -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) -- cgit v1.2.3 From e59399d0102c1813cec48db5cebe1750313f88a0 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 8 Jun 2009 01:39:32 +0900 Subject: nilfs2: correct exclusion control in nilfs_remount function nilfs_remount() changes mount state of a superblock instance. Even though nilfs accesses other superblock instances during mount or remount, the mount state was not properly protected in nilfs_remount(). Moreover, nilfs_remount() has a lock order reversal problem; nilfs_get_sb() holds: 1. bdev->bd_mount_sem 2. sb->s_umount (sget acquires) and nilfs_remount() holds: 1. sb->s_umount (locked by the caller in vfs) 2. bdev->bd_mount_sem To avoid these problems, this patch divides a semaphore protecting super block instances from nilfs->ns_sem, and applies it to the mount state protection in nilfs_remount(). With this change, bd_mount_sem use is removed from nilfs_remount() and the lock order reversal will be resolved. And the new rw-semaphore, nilfs->ns_super_sem will properly protect the mount state except the modification from nilfs_error function. Signed-off-by: Ryusuke Konishi Signed-off-by: Al Viro --- fs/nilfs2/the_nilfs.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/nilfs2/the_nilfs.h') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index be4c040fd62..d0cf4fb7c9c 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_super_sem: semaphore for global operations across super block instances * @ns_writer_mutex: mutex protecting ns_writer attach/detach * @ns_writer_refcount: number of referrers on ns_writer * @ns_current: back pointer to current mount @@ -96,10 +97,15 @@ struct the_nilfs { struct backing_dev_info *ns_bdi; struct nilfs_sb_info *ns_writer; struct rw_semaphore ns_sem; + struct rw_semaphore ns_super_sem; struct mutex ns_writer_mutex; atomic_t ns_writer_refcount; + /* + * components protected by ns_super_sem + */ struct nilfs_sb_info *ns_current; + struct list_head ns_supers; /* * used for @@ -113,7 +119,6 @@ struct the_nilfs { time_t ns_sbwtime[2]; unsigned ns_sbsize; unsigned ns_mount_state; - struct list_head ns_supers; /* * Following fields are dedicated to a writable FS-instance. -- cgit v1.2.3 From aa7dfb8954ccf49e026ba13d12991a4eb7defb96 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 8 Jun 2009 01:39:33 +0900 Subject: nilfs2: get rid of bd_mount_sem use from nilfs This will remove every bd_mount_sem use in nilfs. The intended exclusion control was replaced by the previous patch ("nilfs2: correct exclusion control in nilfs_remount function") for nilfs_remount(), and this patch will replace remains with a new mutex that this inserts in nilfs object. Signed-off-by: Ryusuke Konishi Cc: Christoph Hellwig Signed-off-by: Al Viro --- fs/nilfs2/the_nilfs.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/nilfs2/the_nilfs.h') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index d0cf4fb7c9c..e8adbffc626 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -49,6 +49,7 @@ enum { * @ns_writer: back pointer to writable nilfs_sb_info * @ns_sem: semaphore for shared states * @ns_super_sem: semaphore for global operations across super block instances + * @ns_mount_mutex: mutex protecting mount process of nilfs * @ns_writer_mutex: mutex protecting ns_writer attach/detach * @ns_writer_refcount: number of referrers on ns_writer * @ns_current: back pointer to current mount @@ -98,6 +99,7 @@ struct the_nilfs { struct nilfs_sb_info *ns_writer; struct rw_semaphore ns_sem; struct rw_semaphore ns_super_sem; + struct mutex ns_mount_mutex; struct mutex ns_writer_mutex; atomic_t ns_writer_refcount; -- cgit v1.2.3