flush request is issued in transaction commit code path, so looks using
GFP_KERNEL to allocate memory for flush request bio falls into the classic
deadlock issue. I saw btrfs and dm get it right, but ext4, xfs and md are
using GFP_KERNEL, which makes me confused. Hoping filesystem developers
clarify.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
fs/jbd2/commit.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux/fs/jbd2/commit.c
===================================================================
--- linux.orig/fs/jbd2/commit.c 2012-04-13 09:57:51.785506925 +0800
+++ linux/fs/jbd2/commit.c 2012-04-13 09:58:29.585498773 +0800
@@ -723,7 +723,7 @@ start_journal_io:
if (commit_transaction->t_need_data_flush &&
(journal->j_fs_dev != journal->j_dev) &&
(journal->j_flags & JBD2_BARRIER))
- blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
+ blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
/* Done it all: now write the commit record asynchronously. */
if (JBD2_HAS_INCOMPAT_FEATURE(journal,
@@ -859,7 +859,7 @@ wait_for_iobuf:
if (JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
journal->j_flags & JBD2_BARRIER) {
- blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL);
+ blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
}
if (err)
--
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