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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: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CC:  Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Aneesh Kumar K.V 2009-06-05 01:00:26 -04:00 committed by Theodore Ts'o
parent b31e15527a
commit 1938a150c2
1 changed files with 22 additions and 2 deletions
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24
fs/ext4/inode.c
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@ -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 @@ retry:
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))