ext4: Fix locking hierarchy violation in ext4_fallocate()
ext4_fallocate() was trying to acquire i_data_sem outside of jbd2_start_transaction/jbd2_journal_stop, which violates ext4's locking hierarchy. So we take i_mutex to prevent writes and truncates during the complete fallocate operation, and use ext4_get_block_wrap() which acquires and releases i_data_sem for each block allocation. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -2623,7 +2623,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
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* modify 1 super block, 1 block bitmap and 1 group descriptor.
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*/
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credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
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down_write((&EXT4_I(inode)->i_data_sem));
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mutex_lock(&inode->i_mutex);
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retry:
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while (ret >= 0 && ret < max_blocks) {
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block = block + ret;
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@ -2634,7 +2634,7 @@ retry:
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break;
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}
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ret = ext4_ext_get_blocks(handle, inode, block,
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ret = ext4_get_blocks_wrap(handle, inode, block,
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max_blocks, &map_bh,
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EXT4_CREATE_UNINITIALIZED_EXT, 0);
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WARN_ON(ret <= 0);
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@ -2680,7 +2680,6 @@ retry:
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if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
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goto retry;
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up_write((&EXT4_I(inode)->i_data_sem));
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/*
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* Time to update the file size.
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* Update only when preallocation was requested beyond the file size.
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@ -2692,21 +2691,18 @@ retry:
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* if no error, we assume preallocation succeeded
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* completely
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*/
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mutex_lock(&inode->i_mutex);
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i_size_write(inode, offset + len);
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EXT4_I(inode)->i_disksize = i_size_read(inode);
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mutex_unlock(&inode->i_mutex);
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} else if (ret < 0 && nblocks) {
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/* Handle partial allocation scenario */
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loff_t newsize;
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mutex_lock(&inode->i_mutex);
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newsize = (nblocks << blkbits) + i_size_read(inode);
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i_size_write(inode, EXT4_BLOCK_ALIGN(newsize, blkbits));
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EXT4_I(inode)->i_disksize = i_size_read(inode);
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mutex_unlock(&inode->i_mutex);
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}
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}
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mutex_unlock(&inode->i_mutex);
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return ret > 0 ? ret2 : ret;
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}
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