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Commit 31d710a7 authored by Maciej Żenczykowski's avatar Maciej Żenczykowski Committed by Jan Kara
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ext3: don't update sb journal_devnum when RO dev 



An ext3 filesystem on a read-only device, with an external journal
which is at a different device number then recorded in the superblock
will fail to honor the read-only setting of the device and trigger
a superblock update (write).

For example:
  - ext3 on a software raid which is in read-only mode
  - external journal on a read-write device which has changed device num
  - attempt to mount with -o journal_dev=<new_number>
  - hits BUG_ON(mddev->ro = 1) in md.c

Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarMaciej Żenczykowski <zenczykowski@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 3c0eee3f

fs/ext3/super.c

+1 −1
Original line number Diff line number Diff line
@@ -2290,7 +2290,7 @@ static int ext3_load_journal(struct super_block *sb, 
	EXT3_SB(sb)->s_journal = journal;

	ext3_clear_journal_err(sb, es);



	if (journal_devnum &&

	if (!really_read_only && journal_devnum &&

	    journal_devnum != le32_to_cpu(es->s_journal_dev)) {

		es->s_journal_dev = cpu_to_le32(journal_devnum);