Commit 33c8e57c authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Al Viro
Browse files

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: 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 81fc20bd

fs/nilfs2/super.c

+19 −61
Original line number Diff line number Diff line
@@ -1059,13 +1059,6 @@ 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;



	return s->s_bdev == sd->bdev;

}



static int nilfs_test_bdev_super2(struct super_block *s, void *data)

{

	struct nilfs_super_data *sd = data;

	int ret;
@@ -1096,8 +1089,8 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	     const char *dev_name, void *data, struct vfsmount *mnt)

{

	struct nilfs_super_data sd;

	struct super_block *s, *s2;

	struct the_nilfs *nilfs = NULL;

	struct super_block *s;

	struct the_nilfs *nilfs;

	int err, need_to_close = 1;



	sd.bdev = open_bdev_exclusive(dev_name, flags, fs_type);
@@ -1118,11 +1111,12 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
		goto failed;

	}



	/*

	 * once the super is inserted into the list by sget, s_umount

	 * will protect the lockfs code from trying to start a snapshot

	 * while we are mounting

	 */

	nilfs = find_or_create_nilfs(sd.bdev);

	if (!nilfs) {

		err = -ENOMEM;

		goto failed;

	}



	down(&sd.bdev->bd_mount_sem);

	if (!sd.cno &&

	    (err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {
@@ -1131,51 +1125,22 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	}



	/*

	 * Phase-1: search any existent instance and get the_nilfs

	 */

	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);

	if (IS_ERR(s))

		goto error_s;



	if (!s->s_root) {

		err = -ENOMEM;

		nilfs = alloc_nilfs(sd.bdev);

		if (!nilfs)

			goto cancel_new;

	} else {

		struct nilfs_sb_info *sbi = NILFS_SB(s);



		/*

		 * s_umount protects super_block from unmount process;

		 * It covers pointers of nilfs_sb_info and the_nilfs.

		 */

		nilfs = sbi->s_nilfs;

		get_nilfs(nilfs);

		up_write(&s->s_umount);



		/*

		 * Phase-2: search specified snapshot or R/W mode super_block

	 * Search specified snapshot or R/W mode super_block

	 */

	if (!sd.cno)

		/* trying to get the latest checkpoint.  */

		sd.cno = nilfs_last_cno(nilfs);



		s2 = sget(fs_type, nilfs_test_bdev_super2,

			  nilfs_set_bdev_super, &sd);

		deactivate_super(s);

		/*

		 * Although deactivate_super() invokes close_bdev_exclusive() at

		 * kill_block_super().  Here, s is an existent mount; we need

		 * one more close_bdev_exclusive() call.

		 */

		s = s2;

		if (IS_ERR(s))

			goto error_s;

	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);

	if (IS_ERR(s)) {

		err = PTR_ERR(s);

		goto failed_unlock;

	}



	if (!s->s_root) {

		char b[BDEVNAME_SIZE];



		/* New superblock instance created */

		s->s_flags = flags;

		strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));

		sb_set_blocksize(s, block_size(sd.bdev));
@@ -1195,15 +1160,9 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	simple_set_mnt(mnt, s);

	return 0;



 error_s:

	up(&sd.bdev->bd_mount_sem);

	if (nilfs)

		put_nilfs(nilfs);

	close_bdev_exclusive(sd.bdev, flags);

	return PTR_ERR(s);



 failed_unlock:

	up(&sd.bdev->bd_mount_sem);

	put_nilfs(nilfs);

 failed:

	close_bdev_exclusive(sd.bdev, flags);
@@ -1212,7 +1171,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
 cancel_new:

	/* Abandoning the newly allocated superblock */

	up(&sd.bdev->bd_mount_sem);

	if (nilfs)

	put_nilfs(nilfs);

	up_write(&s->s_umount);

	deactivate_super(s);

fs/nilfs2/the_nilfs.c

+54 −3
Original line number Diff line number Diff line
@@ -35,6 +35,10 @@ 
#include "seglist.h"

#include "segbuf.h"





static LIST_HEAD(nilfs_objects);

static DEFINE_SPINLOCK(nilfs_lock);



void nilfs_set_last_segment(struct the_nilfs *nilfs,

			    sector_t start_blocknr, u64 seq, __u64 cno)

{
@@ -55,7 +59,7 @@ void nilfs_set_last_segment(struct the_nilfs *nilfs, 
 * Return Value: On success, pointer to the_nilfs is returned.

 * On error, NULL is returned.

 */

struct the_nilfs *alloc_nilfs(struct block_device *bdev)

static struct the_nilfs *alloc_nilfs(struct block_device *bdev)

{

	struct the_nilfs *nilfs;
@@ -69,6 +73,7 @@ struct the_nilfs *alloc_nilfs(struct block_device *bdev) 
	atomic_set(&nilfs->ns_ndirtyblks, 0);

	init_rwsem(&nilfs->ns_sem);

	mutex_init(&nilfs->ns_writer_mutex);

	INIT_LIST_HEAD(&nilfs->ns_list);

	INIT_LIST_HEAD(&nilfs->ns_supers);

	spin_lock_init(&nilfs->ns_last_segment_lock);

	nilfs->ns_gc_inodes_h = NULL;
@@ -77,6 +82,45 @@ struct the_nilfs *alloc_nilfs(struct block_device *bdev) 
	return nilfs;

}



/**

 * find_or_create_nilfs - find or create nilfs object

 * @bdev: block device to which the_nilfs is related

 *

 * find_nilfs() looks up an existent nilfs object created on the

 * device and gets the reference count of the object.  If no nilfs object

 * is found on the device, a new nilfs object is allocated.

 *

 * Return Value: On success, pointer to the nilfs object is returned.

 * On error, NULL is returned.

 */

struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)

{

	struct the_nilfs *nilfs, *new = NULL;



 retry:

	spin_lock(&nilfs_lock);

	list_for_each_entry(nilfs, &nilfs_objects, ns_list) {

		if (nilfs->ns_bdev == bdev) {

			get_nilfs(nilfs);

			spin_unlock(&nilfs_lock);

			if (new)

				put_nilfs(new);

			return nilfs; /* existing object */

		}

	}

	if (new) {

		list_add_tail(&new->ns_list, &nilfs_objects);

		spin_unlock(&nilfs_lock);

		return new; /* new object */

	}

	spin_unlock(&nilfs_lock);



	new = alloc_nilfs(bdev);

	if (new)

		goto retry;

	return NULL; /* insufficient memory */

}



/**

 * put_nilfs - release a reference to the_nilfs

 * @nilfs: the_nilfs structure to be released
@@ -86,13 +130,20 @@ struct the_nilfs *alloc_nilfs(struct block_device *bdev) 
 */

void put_nilfs(struct the_nilfs *nilfs)

{

	if (!atomic_dec_and_test(&nilfs->ns_count))

	spin_lock(&nilfs_lock);

	if (!atomic_dec_and_test(&nilfs->ns_count)) {

		spin_unlock(&nilfs_lock);

		return;

	}

	list_del_init(&nilfs->ns_list);

	spin_unlock(&nilfs_lock);



	/*

	 * Increment of ns_count never occur below because the caller

	 * Increment of ns_count never occurs below because the caller

	 * of get_nilfs() holds at least one reference to the_nilfs.

	 * Thus its exclusion control is not required here.

	 */



	might_sleep();

	if (nilfs_loaded(nilfs)) {

		nilfs_mdt_clear(nilfs->ns_sufile);

fs/nilfs2/the_nilfs.h

+3 −1
Original line number Diff line number Diff line
@@ -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 *);

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