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Commit fd98496f authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

jbd2: Add barrier not supported test to journal_wait_on_commit_record 



Xen doesn't report that barriers are not supported until buffer I/O is
reported as completed, instead of when the buffer I/O is submitted.
Add a check and a fallback codepath to journal_wait_on_commit_record()
to detect this case, so that attempts to mount ext4 filesystems on
LVM/devicemapper devices on Xen guests don't blow up with an "Aborting
journal on device XXX"; "Remounting filesystem read-only" error.

Thanks to Andreas Sundstrom for reporting this issue.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
parent 0390131b

fs/jbd2/commit.c

+25 −2
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/crc32.h>

#include <linux/writeback.h>

#include <linux/backing-dev.h>

#include <linux/bio.h>



/*

 * Default IO end handler for temporary BJ_IO buffer_heads.
@@ -168,12 +169,34 @@ static int journal_submit_commit_record(journal_t *journal, 
 * This function along with journal_submit_commit_record

 * allows to write the commit record asynchronously.

 */

static int journal_wait_on_commit_record(struct buffer_head *bh)

static int journal_wait_on_commit_record(journal_t *journal,

					 struct buffer_head *bh)

{

	int ret = 0;



retry:

	clear_buffer_dirty(bh);

	wait_on_buffer(bh);

	if (buffer_eopnotsupp(bh) && (journal->j_flags & JBD2_BARRIER)) {

		printk(KERN_WARNING

		       "JBD2: wait_on_commit_record: sync failed on %s - "

		       "disabling barriers\n", journal->j_devname);

		spin_lock(&journal->j_state_lock);

		journal->j_flags &= ~JBD2_BARRIER;

		spin_unlock(&journal->j_state_lock);



		lock_buffer(bh);

		clear_buffer_dirty(bh);

		set_buffer_uptodate(bh);

		bh->b_end_io = journal_end_buffer_io_sync;



		ret = submit_bh(WRITE_SYNC, bh);

		if (ret) {

			unlock_buffer(bh);

			return ret;

		}

		goto retry;

	}



	if (unlikely(!buffer_uptodate(bh)))

		ret = -EIO;
@@ -799,7 +822,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) 
			__jbd2_journal_abort_hard(journal);

	}

	if (!err && !is_journal_aborted(journal))

		err = journal_wait_on_commit_record(cbh);

		err = journal_wait_on_commit_record(journal, cbh);



	if (err)

		jbd2_journal_abort(journal, err);