Works now :-) Thanks !!! On Tue, Jan 7, 2014 at 8:21 AM, FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote: > On Tue, 07 Jan 2014 22:23:00 +0900 > Hitoshi Mitake <mitake.hitoshi@xxxxxxxxx> wrote: > >> At Tue, 7 Jan 2014 21:59:31 +0900, >> Ryusuke Konishi wrote: >>> >>> The sheepdog driver fails with io errors when write access is >>> requested for a snapshot vdi. The failure happens in create_branch >>> function: >>> >>> tgtd: read_write_object(684) No object found (oid: 8000000 >>> 000000000, old_oid: 0) >>> tgtd: create_branch(1160) reloading new inode object failed >>> tgtd: bs_sheepdog_request(1197) creating writable VDI from >>> snapshot failed >>> >>> sd 12:0:0:1: [sdb] Unhandled sense code >>> sd 12:0:0:1: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE >>> sd 12:0:0:1: [sdb] Sense Key : Medium Error [current] >>> sd 12:0:0:1: [sdb] Add. Sense: Unrecovered read error >>> sd 12:0:0:1: [sdb] CDB: Write(10): 2a 00 00 00 20 a8 00 00 08 00 >>> Buffer I/O error on device sdb1, logical block 1041 >>> lost page write due to I/O error on sdb1 >>> >>> This turned out to be caused by a race condition among multiple write >>> requests. When bs_sheepdog_request() receives a write request for the >>> snapshot vdi, it tries to change the snapshot to a writable vdi with >>> the create_branch function. However, the current implementation of >>> create_branch() cannot handle concurrent requests exclusively nor >>> protected from regular io routine (sd_io). >>> >>> This fixes the above io-error issue by serializing create_branch() >>> with a pthread reader/writer lock, and also fixes the race condition >>> between create_branch() and sd_io() with the lock. >>> >>> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> >>> Cc: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx> >>> --- >>> usr/bs_sheepdog.c | 22 +++++++++++++++++----- >>> 1 file changed, 17 insertions(+), 5 deletions(-) >> >> Ooops, thanks a lot for your fix. It must be a very hard debug and >> sorry for annoying! >> >> Reviewed-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx> > > Applied, thanks a lot, guys. > -- > To unsubscribe from this list: send the line "unsubscribe stgt" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
