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Commit 1938a150 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Ts'o
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ext4: Avoid leaking blocks after a block allocation failure 



We should add inode to the orphan list in the same transaction
as block allocation.  This ensures that if we crash after a failed
block allocation and before we do a vmtruncate we don't leak block
(ie block marked as used in bitmap but not claimed by the inode).

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CC:  Jan Kara <jack@suse.cz>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent b31e1552

fs/ext4/inode.c

+22 −2
Original line number Diff line number Diff line
@@ -1459,7 +1459,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping, 
				struct page **pagep, void **fsdata)

{

	struct inode *inode = mapping->host;

	int ret, needed_blocks = ext4_writepage_trans_blocks(inode);

	int ret, needed_blocks;

	handle_t *handle;

	int retries = 0;

	struct page *page;
@@ -1470,6 +1470,11 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping, 
		   "dev %s ino %lu pos %llu len %u flags %u",

		   inode->i_sb->s_id, inode->i_ino,

		   (unsigned long long) pos, len, flags);

	/*

	 * Reserve one block more for addition to orphan list in case

	 * we allocate blocks but write fails for some reason

	 */

	needed_blocks = ext4_writepage_trans_blocks(inode) + 1;

 	index = pos >> PAGE_CACHE_SHIFT;

	from = pos & (PAGE_CACHE_SIZE - 1);

	to = from + len;
@@ -1503,15 +1508,30 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping, 


	if (ret) {

		unlock_page(page);

		ext4_journal_stop(handle);

		page_cache_release(page);

		/*

		 * block_write_begin may have instantiated a few blocks

		 * outside i_size.  Trim these off again. Don't need

		 * i_size_read because we hold i_mutex.

		 *

		 * Add inode to orphan list in case we crash before

		 * truncate finishes

		 */

		if (pos + len > inode->i_size)

			ext4_orphan_add(handle, inode);



		ext4_journal_stop(handle);

		if (pos + len > inode->i_size) {

			vmtruncate(inode, inode->i_size);

			/* 

			 * If vmtruncate failed early the inode might

			 * still be on the orphan list; we need to

			 * make sure the inode is removed from the

			 * orphan list in that case.

			 */

			if (inode->i_nlink)

				ext4_orphan_del(NULL, inode);

		}

	}



	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))