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Commit 26346ff6 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Ts'o
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ext4: Don't panic in case of corrupt bitmap 



Multiblock allocator calls BUG_ON in many case if the free and used
blocks count obtained looking at the bitmap is different from what
the allocator internally accounted for. Use ext4_error in such case
and don't panic the system.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 256bdb49

fs/ext4/mballoc.c

+21 −14
Original line number Diff line number Diff line
@@ -681,7 +681,6 @@ static void *mb_find_buddy(struct ext4_buddy *e4b, int order, int *max) 
{

	char *bb;



	/* FIXME!! is this needed */

	BUG_ON(EXT4_MB_BITMAP(e4b) == EXT4_MB_BUDDY(e4b));

	BUG_ON(max == NULL);
@@ -965,7 +964,7 @@ static void ext4_mb_generate_buddy(struct super_block *sb, 
	grp->bb_fragments = fragments;



	if (free != grp->bb_free) {

		printk(KERN_DEBUG

		ext4_error(sb, __FUNCTION__,

			"EXT4-fs: group %lu: %u blocks in bitmap, %u in gd\n",

			group, free, grp->bb_free);

		grp->bb_free = free;
@@ -1822,13 +1821,24 @@ static void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac, 
		i = ext4_find_next_zero_bit(bitmap,

						EXT4_BLOCKS_PER_GROUP(sb), i);

		if (i >= EXT4_BLOCKS_PER_GROUP(sb)) {

			BUG_ON(free != 0);

			/*

			 * IF we corrupt the bitmap  we won't find any

			 * free blocks even though group info says we

			 * we have free blocks

			 */

			ext4_error(sb, __FUNCTION__, "%d free blocks as per "

					"group info. But bitmap says 0\n",

					free);

			break;

		}



		mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex);

		BUG_ON(ex.fe_len <= 0);

		BUG_ON(free < ex.fe_len);

		if (free < ex.fe_len) {

			ext4_error(sb, __FUNCTION__, "%d free blocks as per "

					"group info. But got %d blocks\n",

					free, ex.fe_len);

		}



		ext4_mb_measure_extent(ac, &ex, e4b);
@@ -3363,13 +3373,10 @@ static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac, 
	ac->ac_pa = pa;



	/* we don't correct pa_pstart or pa_plen here to avoid

	 * possible race when tte group is being loaded concurrently

	 * possible race when the group is being loaded concurrently

	 * instead we correct pa later, after blocks are marked

	 * in on-disk bitmap -- see ext4_mb_release_context() */

	/*

	 * FIXME!! but the other CPUs can look at this particular

	 * pa and think that it have enought free blocks if we

	 * don't update pa_free here right ?

	 * in on-disk bitmap -- see ext4_mb_release_context()

	 * Other CPUs are prevented from allocating from this pa by lg_mutex

	 */

	mb_debug("use %u/%u from group pa %p\n", pa->pa_lstart-len, len, pa);

}
@@ -3758,13 +3765,13 @@ static int ext4_mb_release_inode_pa(struct ext4_buddy *e4b, 
		bit = next + 1;

	}

	if (free != pa->pa_free) {

		printk(KERN_ERR "pa %p: logic %lu, phys. %lu, len %lu\n",

		printk(KERN_CRIT "pa %p: logic %lu, phys. %lu, len %lu\n",

			pa, (unsigned long) pa->pa_lstart,

			(unsigned long) pa->pa_pstart,

			(unsigned long) pa->pa_len);

		printk(KERN_ERR "free %u, pa_free %u\n", free, pa->pa_free);

		ext4_error(sb, __FUNCTION__, "free %u, pa_free %u\n",

						free, pa->pa_free);

	}

	BUG_ON(free != pa->pa_free);

	atomic_add(free, &sbi->s_mb_discarded);

	if (ac)

		kmem_cache_free(ext4_ac_cachep, ac);
@@ -4435,7 +4442,7 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode, 
			unsigned long block, unsigned long count,

			int metadata, unsigned long *freed)

{

	struct buffer_head *bitmap_bh = 0;

	struct buffer_head *bitmap_bh = NULL;

	struct super_block *sb = inode->i_sb;

	struct ext4_allocation_context *ac = NULL;

	struct ext4_group_desc *gdp;