[Adding lkml on the CC list, somehow I managed to screw the address and sent it to the mm-cc list instead] On Wed, Dec 24, 2008 at 07:10:38PM -0200, Alberto Bertogli wrote: > > Hi! > > I'm writing a small device mapper module, and I'm interested in placing > a jbd/jdb2 journal on the backing device. > > I started by trying to do a __bread() manually (just for early tests) > inside my map function. But it got stucked, as far as I could see, > waiting for a buffer head in wait_on_buffer() IIRC (I could track it > down again if it's needed). And I couldn't find why it was locked, since > it was an unused loopback device, and my code didn't even deal with > buffer heads. > > Then, since I was planning on using jbd/jdb2 anyway, I decided to use it > (and went for jbd2). > > > Now, I'm having issues with journal creation. > > I tried using "mkfs.ext3 -O journal_dev", but jbd2_journal_load() > complains that it can't find the journal superblock. > > And if I modify jbd2_journal_create(), removing the 'if > (journal->j_inode == NULL)' check (I imagine it's there for a reason, > but from a quick look at the code couldn't find it and thought it was > worth a try) then when creating it I get a warning (pasted below) and it > gets locked up, which I think may be related to what happened when I did > __bread(), but obviously I'm not sure at all. > > And I got stucked there, so I thought it'd be better to ask. Does anyone > have any ideas or suggestions on what I'm doing wrong? > > > I've not published my code yet because it's really rough, but if anyone > wants to take a look at it, please let me know. I was planning on > posting it when it was at least working. > > Thanks a lot, > Alberto > > > > [42949814.780000] ------------[ cut here ]------------ > [42949814.780000] WARNING: at /pub/src/linux/linux-2.6/fs/buffer.c:1186 mark_buffer_dirty+0x77/0xa0() > [42949814.780000] Modules linked in: > [42949814.780000] Call Trace: > [42949814.780000] 678f17d8: [<6003988b>] warn_on_slowpath+0x5b/0x80 > [42949814.780000] 678f1818: [<600bbe9a>] __find_get_block_slow+0x7a/0x110 > [42949814.780000] 678f1858: [<600bc219>] __find_get_block+0x79/0x180 > [42949814.780000] 678f1888: [<60033b05>] __might_sleep+0x105/0x130 > [42949814.780000] 678f18c8: [<600bc353>] __getblk+0x33/0x270 > [42949814.780000] 678f18f8: [<600bc7e7>] mark_buffer_dirty+0x77/0xa0 > [42949814.780000] 678f1918: [<6012b1a8>] jbd2_journal_create+0x88/0x170 > [42949814.780000] 678f1958: [<601aac70>] csum_ctr+0x1b0/0x240 > [42949814.780000] 678f1968: [<6019b810>] get_target_type+0x60/0xa0 > [42949814.780000] 678f19a8: [<6019b0d4>] dm_table_add_target+0x174/0x3b0 > [42949814.780000] 678f1a08: [<6019d057>] table_load+0xb7/0x200 > [42949814.780000] 678f1a68: [<6019dd98>] dm_ctl_ioctl+0x288/0x300 > [42949814.780000] 678f1a98: [<6019cfa0>] table_load+0x0/0x200 > [42949814.780000] 678f1c18: [<600a82fb>] vfs_ioctl+0x1b/0x70 > [42949814.780000] 678f1c28: [<600a8770>] do_vfs_ioctl+0x400/0x660 > [42949814.780000] 678f1ca8: [<600a8a1a>] sys_ioctl+0x4a/0x80 > [42949814.780000] 678f1ce8: [<6001a310>] handle_syscall+0x50/0x80 > [42949814.780000] 678f1d08: [<6002bf1f>] userspace+0x3ff/0x530 > [42949814.780000] 678f1fc8: [<60017012>] fork_handler+0x62/0x70 > [42949814.780000] > [42949814.780000] ---[ end trace ebc125a00ee8f9d2 ]--- -- 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
