ext4: use transaction reservation for extent conversion in ext4_end_io
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>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 736d164..510dba7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1410,6 +1410,7 @@
struct mpage_da_data {
struct inode *inode;
struct writeback_control *wbc;
+
pgoff_t first_page; /* The first page to write */
pgoff_t next_page; /* Current page to examine */
pgoff_t last_page; /* Last page to examine */
@@ -2108,8 +2109,14 @@
err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
if (err < 0)
return err;
- if (map->m_flags & EXT4_MAP_UNINIT)
+ if (map->m_flags & EXT4_MAP_UNINIT) {
+ if (!mpd->io_submit.io_end->handle &&
+ ext4_handle_valid(handle)) {
+ mpd->io_submit.io_end->handle = handle->h_rsv_handle;
+ handle->h_rsv_handle = NULL;
+ }
ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
+ }
BUG_ON(map->m_len == 0);
if (map->m_flags & EXT4_MAP_NEW) {
@@ -2351,7 +2358,7 @@
handle_t *handle = NULL;
struct mpage_da_data mpd;
struct inode *inode = mapping->host;
- int needed_blocks, ret = 0;
+ int needed_blocks, rsv_blocks = 0, ret = 0;
struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
bool done;
struct blk_plug plug;
@@ -2379,6 +2386,14 @@
if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
return -EROFS;
+ if (ext4_should_dioread_nolock(inode)) {
+ /*
+ * We may need to convert upto one extent per block in
+ * the page and we may dirty the inode.
+ */
+ rsv_blocks = 1 + (PAGE_CACHE_SIZE >> inode->i_blkbits);
+ }
+
/*
* If we have inline data and arrive here, it means that
* we will soon create the block for the 1st page, so
@@ -2438,8 +2453,8 @@
needed_blocks = ext4_da_writepages_trans_blocks(inode);
/* start a new transaction */
- handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
- needed_blocks);
+ handle = ext4_journal_start_with_reserve(inode,
+ EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
@@ -3120,7 +3135,7 @@
* for non AIO case, since the IO is already
* completed, we could do the conversion right here
*/
- err = ext4_convert_unwritten_extents(inode,
+ err = ext4_convert_unwritten_extents(NULL, inode,
offset, ret);
if (err < 0)
ret = err;