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ext4: use transaction reservation for extent conversion in ext4_end_io

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Later we would like to clear PageWriteback bit only after extent
conversion from unwritten to written extents is performed.  However it
is not possible to start a transaction after PageWriteback is set
because that violates lock ordering (and is easy to deadlock).  So we
have to reserve a transaction before locking pages and sending them
for IO and later we use the transaction for extent conversion from
ext4_end_io().

Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara
2013-06-04 13:21:11 -04:00
committed by Theodore Ts'o
parent 3613d22807
commit 6b523df4fb
5 changed files with 69 additions and 24 deletions
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40
fs/ext4/extents.c
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@@ -4566,10 +4566,9 @@ retry:
* function, to convert the fallocated extents after IO is completed.
* Returns 0 on success.
*/
int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
ssize_t len)
int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
loff_t offset, ssize_t len)
{
handle_t *handle;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
@@ -4584,16 +4583,32 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -
map.m_lblk);
/*
* credits to insert 1 extent into extent tree
* This is somewhat ugly but the idea is clear: When transaction is
* reserved, everything goes into it. Otherwise we rather start several
* smaller transactions for conversion of each extent separately.
*/
credits = ext4_chunk_trans_blocks(inode, max_blocks);
if (handle) {
handle = ext4_journal_start_reserved(handle,
EXT4_HT_EXT_CONVERT);
if (IS_ERR(handle))
return PTR_ERR(handle);
credits = 0;
} else {
/*
* credits to insert 1 extent into extent tree
*/
credits = ext4_chunk_trans_blocks(inode, max_blocks);
}
while (ret >= 0 && ret < max_blocks) {
map.m_lblk += ret;
map.m_len = (max_blocks -= ret);
handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
if (credits) {
handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
}
}
ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_IO_CONVERT_EXT);
@@ -4604,10 +4619,13 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
inode->i_ino, map.m_lblk,
map.m_len, ret);
ext4_mark_inode_dirty(handle, inode);
ret2 = ext4_journal_stop(handle);
if (ret <= 0 || ret2 )
if (credits)
ret2 = ext4_journal_stop(handle);
if (ret <= 0 || ret2)
break;
}
if (!credits)
ret2 = ext4_journal_stop(handle);
return ret > 0 ? ret2 : ret;
}