diff options
Diffstat (limited to 'fs/super.c')
-rw-r--r-- | fs/super.c | 66 |
1 files changed, 42 insertions, 24 deletions
diff --git a/fs/super.c b/fs/super.c index 816a22a5cad1..77faad662739 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1422,32 +1422,48 @@ EXPORT_SYMBOL(sget_dev); #ifdef CONFIG_BLOCK /* - * Lock a super block that the callers holds a reference to. + * Lock the superblock that is holder of the bdev. Returns the superblock + * pointer if we successfully locked the superblock and it is alive. Otherwise + * we return NULL and just unlock bdev->bd_holder_lock. * - * The caller needs to ensure that the super_block isn't being freed while - * calling this function, e.g. by holding a lock over the call to this function - * and the place that clears the pointer to the superblock used by this function - * before freeing the superblock. + * The function must be called with bdev->bd_holder_lock and releases it. */ -static bool super_lock_shared_active(struct super_block *sb) +static struct super_block *bdev_super_lock_shared(struct block_device *bdev) + __releases(&bdev->bd_holder_lock) { - bool born = super_lock_shared(sb); + struct super_block *sb = bdev->bd_holder; + bool born; + + lockdep_assert_held(&bdev->bd_holder_lock); + lockdep_assert_not_held(&sb->s_umount); + lockdep_assert_not_held(&bdev->bd_disk->open_mutex); + + /* Make sure sb doesn't go away from under us */ + spin_lock(&sb_lock); + sb->s_count++; + spin_unlock(&sb_lock); + mutex_unlock(&bdev->bd_holder_lock); + born = super_lock_shared(sb); if (!born || !sb->s_root || !(sb->s_flags & SB_ACTIVE)) { super_unlock_shared(sb); - return false; + put_super(sb); + return NULL; } - return true; + /* + * The superblock is active and we hold s_umount, we can drop our + * temporary reference now. + */ + put_super(sb); + return sb; } static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) { - struct super_block *sb = bdev->bd_holder; - - /* bd_holder_lock ensures that the sb isn't freed */ - lockdep_assert_held(&bdev->bd_holder_lock); + struct super_block *sb; - if (!super_lock_shared_active(sb)) + sb = bdev_super_lock_shared(bdev); + if (!sb) return; if (!surprise) @@ -1462,11 +1478,10 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) static void fs_bdev_sync(struct block_device *bdev) { - struct super_block *sb = bdev->bd_holder; - - lockdep_assert_held(&bdev->bd_holder_lock); + struct super_block *sb; - if (!super_lock_shared_active(sb)) + sb = bdev_super_lock_shared(bdev); + if (!sb) return; sync_filesystem(sb); super_unlock_shared(sb); @@ -1482,14 +1497,16 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, struct fs_context *fc) { blk_mode_t mode = sb_open_mode(sb_flags); + struct bdev_handle *bdev_handle; struct block_device *bdev; - bdev = blkdev_get_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); - if (IS_ERR(bdev)) { + bdev_handle = bdev_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); + if (IS_ERR(bdev_handle)) { if (fc) errorf(fc, "%s: Can't open blockdev", fc->source); - return PTR_ERR(bdev); + return PTR_ERR(bdev_handle); } + bdev = bdev_handle->bdev; /* * This really should be in blkdev_get_by_dev, but right now can't due @@ -1497,7 +1514,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, * writable from userspace even for a read-only block device. */ if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) { - blkdev_put(bdev, sb); + bdev_release(bdev_handle); return -EACCES; } @@ -1513,10 +1530,11 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, mutex_unlock(&bdev->bd_fsfreeze_mutex); if (fc) warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); - blkdev_put(bdev, sb); + bdev_release(bdev_handle); return -EBUSY; } spin_lock(&sb_lock); + sb->s_bdev_handle = bdev_handle; sb->s_bdev = bdev; sb->s_bdi = bdi_get(bdev->bd_disk->bdi); if (bdev_stable_writes(bdev)) @@ -1649,7 +1667,7 @@ void kill_block_super(struct super_block *sb) generic_shutdown_super(sb); if (bdev) { sync_blockdev(bdev); - blkdev_put(bdev, sb); + bdev_release(sb->s_bdev_handle); } } |