This patch checks for and prevents the deadlock with a page in
journalled writeback in ext4_write_begin().
Finally, add wait_on_page_writeback() if data=journal mode.
Note: similar changes are not needed in ext4_da_write_begin()
as delayed allocation is not applicable to data journalling
(different struct address_space_operations).
Signed-off-by: Mauricio Faria de Oliveira <mfo@xxxxxxxxxxxxx>
---
fs/ext4/inode.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 401313be8a5b..f58c426aaca1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1149,6 +1149,8 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
+ if (ext4_should_journal_data(inode))
+ wait_on_page_writeback(page);
unlock_page(page);
retry_journal:
@@ -1165,9 +1167,19 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
put_page(page);
ext4_journal_stop(handle);
goto retry_grab;
+ } else if (ext4_should_journal_data(inode) &&
+ ext4_check_journalled_writeback(handle, page)) {
+ /* Or transaction may block page writeback */
+ unlock_page(page);
+ put_page(page);
+ ext4_journal_stop(handle);
+ ext4_start_commit_datasync(inode);
+ goto retry_grab;
}
/* In case writeback began while the page was unlocked */
wait_for_stable_page(page);
+ if (ext4_should_journal_data(inode))
+ wait_on_page_writeback(page);
#ifdef CONFIG_FS_ENCRYPTION
if (ext4_should_dioread_nolock(inode))
--
2.20.1
