>> We want this for btrfs_extent_same. Basically readpage and friends do their >> own extent locking but for the purposes of dedupe, we want to have both >> files locked down across a set of readpage operations (so that we can >> compare data). Introduce this variant and a flag which can be set for >> extent_read_full_page() to indicate that we are already locked. > > This one can get stuck in TASK_UNINTERRUPTIBLE: > > [32129.522257] SysRq : Show Blocked State > [32129.524337] task PC stack pid father > [32129.526515] python D ffff88021f394280 0 16281 1 > 0x00000004 > [32129.528656] ffff88020e079a48 0000000000000082 ffff88013d3cdd40 > ffff88020e079fd8 > [32129.530840] ffff88020e079fd8 ffff88020e079fd8 ffff8802138dc5f0 > ffff88013d3cdd40 > [32129.533044] 0000000000000000 0000000000001fff ffff88015286f440 > 0000000000000008 > [32129.535285] Call Trace: > [32129.537522] [<ffffffff816dcca9>] schedule+0x29/0x70 > [32129.539829] [<ffffffffa02b4908>] wait_extent_bit+0xf8/0x150 [btrfs] > [32129.542130] [<ffffffff8107ea00>] ? finish_wait+0x80/0x80 > [32129.544463] [<ffffffffa02b4f84>] lock_extent_bits+0x44/0xa0 [btrfs] > [32129.546824] [<ffffffffa02b4ff3>] lock_extent+0x13/0x20 [btrfs] > [32129.549198] [<ffffffffa02dc0cf>] add_ra_bio_pages.isra.8+0x17f/0x2d0 > [btrfs] > [32129.551602] [<ffffffffa02dccfc>] btrfs_submit_compressed_read+0x25c/0x4c0 > [btrfs] > [32129.554028] [<ffffffffa029d131>] btrfs_submit_bio_hook+0x1d1/0x1e0 [btrfs] > [32129.556457] [<ffffffffa02b2d07>] submit_one_bio+0x67/0xa0 [btrfs] > [32129.558899] [<ffffffffa02b7ecd>] extent_read_full_page_nolock+0x4d/0x60 > [btrfs] > [32129.561290] [<ffffffffa02c8052>] fill_data+0xb2/0x230 [btrfs] > [32129.563623] [<ffffffffa02cd57e>] btrfs_ioctl+0x1f7e/0x2560 [btrfs] > [32129.565924] [<ffffffff816ddbae>] ? _raw_spin_lock+0xe/0x20 > [32129.568207] [<ffffffff8119b907>] ? inode_get_bytes+0x47/0x60 > [32129.570472] [<ffffffff811a8297>] do_vfs_ioctl+0x97/0x560 > [32129.572700] [<ffffffff8119bb5a>] ? sys_newfstat+0x2a/0x40 > [32129.574882] [<ffffffff811a87f1>] sys_ioctl+0x91/0xb0 > [32129.577008] [<ffffffff816e64dd>] system_call_fastpath+0x1a/0x1f
For anyone trying those patches, there's a fix here: https://github.com/g2p/linux/tree/v3.9%2Bbtrfs-extent-same -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
