If you do something like: # touch foo # tail -f foo & # rm foo # <take snapshot> # <mount snapshot> you'll panic, because ext3/4 tries to do orphan list processing on the readonly snapshot device, and: kernel: journal commit I/O error kernel: Assertion failure in journal_flush_Rsmp_e2f189ce() at journal.c:1356: "!journal->j_checkpoint_transactions" kernel: Kernel panic: Fatal exception for a truly readonly underlying device, it's reasonable and necessary to just skip orphan list processing. Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> Index: linux-2.6.18/fs/ext3/super.c =================================================================== --- linux-2.6.18.orig/fs/ext3/super.c +++ linux-2.6.18/fs/ext3/super.c @@ -1264,6 +1264,12 @@ static void ext3_orphan_cleanup (struct return; } + if (bdev_read_only(sb->s_bdev)) { + printk(KERN_ERR "EXT3-fs: write access " + "unavailable, skipping orphan cleanup.\n"); + return; + } + if (EXT3_SB(sb)->s_mount_state & EXT3_ERROR_FS) { if (es->s_last_orphan) jbd_debug(1, "Errors on filesystem, " Index: linux-2.6.18/fs/ext4/super.c =================================================================== --- linux-2.6.18.orig/fs/ext4/super.c +++ linux-2.6.18/fs/ext4/super.c @@ -1321,6 +1321,12 @@ static void ext4_orphan_cleanup (struct return; } + if (bdev_read_only(sb->s_bdev)) { + printk(KERN_ERR "EXT4-fs: write access " + "unavailable, skipping orphan cleanup.\n"); + return; + } + if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) { if (es->s_last_orphan) jbd_debug(1, "Errors on filesystem, " - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html