From: Jeffrey Mahoney This patch fixes a race between mount and umount in set_blocksize. The results can vary between buffer errors and infinite loops in __getblk_slow, and possibly others. The patch makes set_blocksize run under the bdev_lock if it is the sole holder of the block device. Changes: - Added missing sync_blockdev in kill_block_super, lost in the shuffle. Signed-off-by: Jeff Mahoney Signed-off-by: Andrew Morton --- 25-akpm/fs/block_dev.c | 24 ++++++++++++------------ 25-akpm/fs/super.c | 4 ++-- 25-akpm/include/linux/fs.h | 19 ++++++++++++++++--- 3 files changed, 30 insertions(+), 17 deletions(-) diff -puN fs/block_dev.c~blockdev-fixes-race-between-mount-umount fs/block_dev.c --- 25/fs/block_dev.c~blockdev-fixes-race-between-mount-umount Sun Mar 6 16:17:52 2005 +++ 25-akpm/fs/block_dev.c Sun Mar 6 16:17:52 2005 @@ -62,7 +62,7 @@ static void kill_bdev(struct block_devic truncate_inode_pages(bdev->bd_inode->i_mapping, 0); } -int set_blocksize(struct block_device *bdev, int size) +int __set_blocksize(struct block_device *bdev, int size, int sync) { /* Size must be a power of two, and between 512 and PAGE_SIZE */ if (size > PAGE_SIZE || size < 512 || (size & (size-1))) @@ -74,15 +74,15 @@ int set_blocksize(struct block_device *b /* Don't change the size if it is same as current */ if (bdev->bd_block_size != size) { - sync_blockdev(bdev); + if (sync) + sync_blockdev(bdev); bdev->bd_block_size = size; bdev->bd_inode->i_blkbits = blksize_bits(size); kill_bdev(bdev); } return 0; } - -EXPORT_SYMBOL(set_blocksize); +EXPORT_SYMBOL(__set_blocksize); int sb_set_blocksize(struct super_block *sb, int size) { @@ -477,20 +477,20 @@ int bd_claim(struct block_device *bdev, spin_unlock(&bdev_lock); return res; } - EXPORT_SYMBOL(bd_claim); -void bd_release(struct block_device *bdev) +void __bd_release(struct block_device *bdev, int size) { spin_lock(&bdev_lock); if (!--bdev->bd_contains->bd_holders) bdev->bd_contains->bd_holder = NULL; - if (!--bdev->bd_holders) + if (!--bdev->bd_holders) { bdev->bd_holder = NULL; + set_blocksize_nosync (bdev, size); + } spin_unlock(&bdev_lock); } - -EXPORT_SYMBOL(bd_release); +EXPORT_SYMBOL(__bd_release); /* * Tries to open block device by device number. Use it ONLY if you @@ -914,10 +914,10 @@ EXPORT_SYMBOL(open_bdev_excl); * * This is the counterpart to open_bdev_excl(). */ -void close_bdev_excl(struct block_device *bdev) +void __close_bdev_excl(struct block_device *bdev, int size) { - bd_release(bdev); + __bd_release(bdev, size); blkdev_put(bdev); } -EXPORT_SYMBOL(close_bdev_excl); +EXPORT_SYMBOL(__close_bdev_excl); diff -puN fs/super.c~blockdev-fixes-race-between-mount-umount fs/super.c --- 25/fs/super.c~blockdev-fixes-race-between-mount-umount Sun Mar 6 16:17:52 2005 +++ 25-akpm/fs/super.c Sun Mar 6 16:17:52 2005 @@ -732,8 +732,8 @@ void kill_block_super(struct super_block bdev_uevent(bdev, KOBJ_UMOUNT); generic_shutdown_super(sb); - set_blocksize(bdev, sb->s_old_blocksize); - close_bdev_excl(bdev); + sync_blockdev(bdev); + __close_bdev_excl(bdev, sb->s_old_blocksize); } EXPORT_SYMBOL(kill_block_super); diff -puN include/linux/fs.h~blockdev-fixes-race-between-mount-umount include/linux/fs.h --- 25/include/linux/fs.h~blockdev-fixes-race-between-mount-umount Sun Mar 6 16:17:52 2005 +++ 25-akpm/include/linux/fs.h Sun Mar 6 16:17:56 2005 @@ -1290,7 +1290,10 @@ extern long compat_blkdev_ioctl(struct f extern int blkdev_get(struct block_device *, mode_t, unsigned); extern int blkdev_put(struct block_device *); extern int bd_claim(struct block_device *, void *); -extern void bd_release(struct block_device *); +extern void __bd_release(struct block_device *, int); +static inline void bd_release(struct block_device *bdev) { + __bd_release (bdev, bdev->bd_block_size); +} /* fs/char_dev.c */ extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *); @@ -1307,7 +1310,10 @@ extern const char *__bdevname(dev_t, cha extern const char *bdevname(struct block_device *bdev, char *buffer); extern struct block_device *lookup_bdev(const char *); extern struct block_device *open_bdev_excl(const char *, int, void *); -extern void close_bdev_excl(struct block_device *); +extern void __close_bdev_excl(struct block_device *, int); +static inline void close_bdev_excl(struct block_device *bdev) { + __close_bdev_excl(bdev, bdev->bd_block_size); +} extern void init_special_inode(struct inode *, umode_t, dev_t); @@ -1447,7 +1453,14 @@ extern void file_kill(struct file *f); struct bio; extern void submit_bio(int, struct bio *); extern int bdev_read_only(struct block_device *); -extern int set_blocksize(struct block_device *, int); +extern int __set_blocksize(struct block_device *, int, int); +static inline int set_blocksize(struct block_device *bdev, int size) { + return __set_blocksize (bdev, size, 1); +} +static inline int set_blocksize_nosync(struct block_device *bdev, int size) { + return __set_blocksize (bdev, size, 0); +} + extern int sb_set_blocksize(struct super_block *, int); extern int sb_min_blocksize(struct super_block *, int); _