ext4: Fix lockdep recursive locking warning
In ext4_mb_init_group(), if the filesystem block size is less than PAGE_SIZE/2, the code tries to grab alloc_sem for multiple block groups in a loop. We need to allow for this by using down_write_nested() and passing in the loop index as a lock subclass number. This works because no other code path needs to take multiple alloc_sem's. Note that lockdep will fail for filesystem blocksize smaller than to PAGE_SIZE/16k. (e.g., a 1k filesystem blocksize with a 32k page size, or a 2k filesystem blocksize with a 64k blocksize, etc.) Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -1780,7 +1780,7 @@ int ext4_mb_get_buddy_cache_lock(struct super_block *sb, ext4_group_t group)
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* no block allocation going on in any
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* of that groups
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*/
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down_write(&grp->alloc_sem);
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down_write_nested(&grp->alloc_sem, i);
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}
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return i;
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}
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