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>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index bc7081f..e856f66 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2623,7 +2623,7 @@
* modify 1 super block, 1 block bitmap and 1 group descriptor.
*/
credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
- down_write((&EXT4_I(inode)->i_data_sem));
+ mutex_lock(&inode->i_mutex);
retry:
while (ret >= 0 && ret < max_blocks) {
block = block + ret;
@@ -2634,7 +2634,7 @@
break;
}
- ret = ext4_ext_get_blocks(handle, inode, block,
+ ret = ext4_get_blocks_wrap(handle, inode, block,
max_blocks, &map_bh,
EXT4_CREATE_UNINITIALIZED_EXT, 0);
WARN_ON(ret <= 0);
@@ -2680,7 +2680,6 @@
if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
- up_write((&EXT4_I(inode)->i_data_sem));
/*
* Time to update the file size.
* Update only when preallocation was requested beyond the file size.
@@ -2692,21 +2691,18 @@
* if no error, we assume preallocation succeeded
* completely
*/
- mutex_lock(&inode->i_mutex);
i_size_write(inode, offset + len);
EXT4_I(inode)->i_disksize = i_size_read(inode);
- mutex_unlock(&inode->i_mutex);
} else if (ret < 0 && nblocks) {
/* Handle partial allocation scenario */
loff_t newsize;
- mutex_lock(&inode->i_mutex);
newsize = (nblocks << blkbits) + i_size_read(inode);
i_size_write(inode, EXT4_BLOCK_ALIGN(newsize, blkbits));
EXT4_I(inode)->i_disksize = i_size_read(inode);
- mutex_unlock(&inode->i_mutex);
}
}
+ mutex_unlock(&inode->i_mutex);
return ret > 0 ? ret2 : ret;
}