On Thu, Nov 24, 2016 at 11:13:37AM +0000, Filipe Manana wrote: > On Wed, Nov 23, 2016 at 9:22 PM, Liu Bo <bo.li....@oracle.com> wrote: > > Hi, > > > > On Wed, Nov 23, 2016 at 06:21:35PM +0100, Stefan Priebe - Profihost AG > > wrote: > >> Hi, > >> > >> sorry last mail was from the wrong box. > >> > >> Am 04.11.2016 um 20:20 schrieb Liu Bo: > >> > If we have > >> > > >> > |0--hole--4095||4096--preallocate--12287| > >> > > >> > instead of using preallocated space, a 8K direct write will just > >> > create a new 8K extent and it'll end up with > >> > > >> > |0--new extent--8191||8192--preallocate--12287| > >> > > >> > It's because we find a hole em and then go to create a new 8K > >> > extent directly without adjusting @len. > >> > >> after applying that one on top of my 4.4 btrfs branch (includes patches > >> up to 4.10 / next). i'm getting deadlocks in btrfs. > > > > This is really interesting, thanks for the quick testing. > > > > After going through the stacks listed below, I think the patch has > > exposed a bug around BTRFS_I(inode)->dio_sem: > > > > 1. Since fsync has acquired inode_lock(), the dio write must be > > an overwrite within EOF. > > > > 2. Lets say the inode size is 16k and it already has a preallocated extent > > [4k, 8k], > > then we feed it with a dio write against [0k, 8k], with this patch > > applied, the write can be splitted into a new extent of [0, 4k] and a > > fill-write against the preallocated one [4k, 8k], > > > > 3. > > dio fsync > > ->btrfs_direct_IO > > btrfs_sync_file > > ->do_direct_IO > > ->get_more_blocks() > > ->inode_lock() > > ->btrfs_get_blocks_direct() # for [0, 8k] > > ->btrfs_log_inode() > > ->btrfs_new_direct_extent() > > ->btrfs_log_changed_extents() > > ->btrfs_create_dio_extent() > > ->down_read(&BTRFS_I(inode)->dio_sem) > > # dio write is splitted and > > # em of [0, 4k] is inserted as well as > > # the ordered extent. > > ->up_read(&BTRFS_I(inode)->dio_sem) > > # do_direct_IO tries to collect more pages > > # before sending them down, so [0, 4k] is not > > # yet submitted. > > -------------------------------------------------------------------------------------------------------- > > > > ->down_write(&BTRFS_I(inode)->dio_sem) > > # > > found ordered extent of [0, 4k] > > # > > wait for [0, 4k] to finish > > ->get_more_blocks() > > ->btrfs_get_blocks_direct() # for [4k, 8k] > > ->btrfs_create_dio_extent() > > -> up_read(&BTRFS_I(inode)->dio_sem) > > # deadlock occurs > > > > 4. _Without_ this patch, we could hit the deadlock as well under space > > pressure, > > i.e. if we request [0, 8k], but btrfs_reserve_extent() returns only [0, 4k]. > > > > (Filipe may correct me, cc'd Filipe.) > > The analysis is correct Bo. > Originally to fix races between fsync and direct IO writes there was a > solution [1, 2] that didn't involve adding a semaphore and relied on > creating first the ordered extents and then the extent maps only in > the direct IO write path (we do things in the reverse order everywhere > else). It worked and was documented in comments but wasn't > particularly elegant and Josef was not happy because of that, so then > we added the semaphore and made direct IO write path create the extent > maps and ordered extents in the same order as everywhere else [3]. > > So here I can only see 2 simple solutions. Either revert [3] (which > added the semaphore) or acquire the semaphore at a higher level in > direct IO write path like this: > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 1f980ef..b2c277d 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -7237,7 +7237,6 @@ static struct extent_map > *btrfs_create_dio_extent(struct inode *inode, > struct extent_map *em = NULL; > int ret; > > - down_read(&BTRFS_I(inode)->dio_sem); > if (type != BTRFS_ORDERED_NOCOW) { > em = create_pinned_em(inode, start, len, orig_start, > block_start, block_len, orig_block_len, > @@ -7256,8 +7255,6 @@ static struct extent_map > *btrfs_create_dio_extent(struct inode *inode, > em = ERR_PTR(ret); > } > out: > - up_read(&BTRFS_I(inode)->dio_sem); > - > return em; > } > > @@ -8715,11 +8712,14 @@ static ssize_t btrfs_direct_IO(struct kiocb > *iocb, struct iov_iter *iter) > wakeup = false; > } > > + if (iov_iter_rw(iter) == WRITE) > + down_read(&BTRFS_I(inode)->dio_sem); > ret = __blockdev_direct_IO(iocb, inode, > > BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev, > iter, btrfs_get_blocks_direct, NULL, > btrfs_submit_direct, flags); > if (iov_iter_rw(iter) == WRITE) { > + up_read(&BTRFS_I(inode)->dio_sem); > current->journal_info = NULL; > if (ret < 0 && ret != -EIOCBQUEUED) { > if (dio_data.reserve) > > > Let me know what you think. Thanks.
Hi Filipe, After going over again fs/direct-io.c, the AIO dio_complete is diffrent from the 'Note that' part in your patch [1], what am I missing? ------------------------------------------------------------------------- static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async) { ... if (!(dio->flags & DIO_SKIP_DIO_COUNT)) inode_dio_end(dio->inode); if (is_async) { /* * generic_write_sync expects ki_pos to have been updated * already, but the submission path only does this for * synchronous I/O. */ dio->iocb->ki_pos += transferred; if (dio->op == REQ_OP_WRITE) ret = generic_write_sync(dio->iocb, transferred); dio->iocb->ki_complete(dio->iocb, ret, 0); } ... } ------------------------------------------------------------------------- [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=de0ee0edb21fbab4c7afa3e94573ecfebfb0244e Thanks, -liubo > > [1] > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=de0ee0edb21fbab4c7afa3e94573ecfebfb0244e > [2] > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0b901916a00bc7b14ee83cc8e41c3b0d561a8f22 > [3] > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af > > > > > > Thanks, > > > > -liubo > > > >> > >> Traces here: > >> INFO: task btrfs-transacti:604 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> btrfs-transacti D ffff8814e78cbe00 0 604 2 0x00080000 > >> ffff8814e78cbe00 ffff88017367a540 ffff8814e2f88000 ffff8814e78cc000 > >> ffff8814e78cbe38 ffff88123616c510 ffff8814e24c81f0 ffff88153fb0a000 > >> ffff8814e78cbe18 ffffffff816a8425 ffff8814e63165a0 ffff8814e78cbe88 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03751a5>] btrfs_commit_transaction+0x275/0xa50 [btrfs] > >> [<ffffffffc036fdd6>] transaction_kthread+0x1d6/0x200 [btrfs] > >> [<ffffffff810a0cbb>] kthread+0xdb/0x100 > >> [<ffffffff816ac84f>] ret_from_fork+0x3f/0x70 > >> DWARF2 unwinder stuck at ret_from_fork+0x3f/0x70 > >> > >> Leftover inexact backtrace: > >> > >> [<ffffffff810a0be0>] ? kthread_park+0x60/0x60 > >> INFO: task mysqld:1977 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff88142ef1bcf8 0 1977 1 0x00080000 > >> ffff88142ef1bcf8 ffffffff81e0f500 ffff8814dc2c4a80 ffff88142ef1c000 > >> ffff8814e32ed298 ffff8814e32ed2c0 ffff88110aa9a000 ffff8814e32ed000 > >> ffff88142ef1bd10 ffffffff816a8425 ffff8814e32ed000 ffff88142ef1bd60 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03b38a2>] wait_for_writer+0xa2/0xb0 [btrfs] > >> [<ffffffffc03bb439>] btrfs_sync_log+0xe9/0xa00 [btrfs] > >> [<ffffffffc038d1bf>] btrfs_sync_file+0x35f/0x3d0 [btrfs] > >> [<ffffffff8120055d>] vfs_fsync_range+0x3d/0xb0 > >> [<ffffffff8120062d>] do_fsync+0x3d/0x70 > >> [<ffffffff812008a0>] SyS_fsync+0x10/0x20 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x71 > >> > >> Leftover inexact backtrace: > >> > >> INFO: task mysqld:3249 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff881475fdfa40 0 3249 1 0x00080000 > >> ffff881475fdfa40 ffff88017367ca80 ffff8814433d2540 ffff881475fe0000 > >> ffff88040da39ba0 0000000000230000 ffff88040da39c20 0000000000238000 > >> ffff881475fdfa58 ffffffff816a8425 0000000000008000 ffff881475fdfb18 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03b4cb7>] > >> wait_ordered_extents.isra.18.constprop.23+0x147/0x3d0 [btrfs] > >> [<ffffffffc03b5182>] btrfs_log_changed_extents+0x242/0x610 [btrfs] > >> [<ffffffffc03ba6a4>] btrfs_log_inode+0x874/0xb80 [btrfs] > >> [<ffffffffc03bac6c>] btrfs_log_inode_parent+0x22c/0x910 [btrfs] > >> [<ffffffffc03bc292>] btrfs_log_dentry_safe+0x62/0x80 [btrfs] > >> [<ffffffffc038d0ec>] btrfs_sync_file+0x28c/0x3d0 [btrfs] > >> [<ffffffff8120055d>] vfs_fsync_range+0x3d/0xb0 > >> [<ffffffff8120062d>] do_fsync+0x3d/0x70 > >> [<ffffffff812008a0>] SyS_fsync+0x10/0x20 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x71 > >> > >> Leftover inexact backtrace: > >> > >> INFO: task mysqld:3250 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff881374edb868 0 3250 1 0x00080000 > >> ffff881374edb868 ffff8801736b2540 ffff8814433d4a80 ffff881374edc000 > >> ffff8814e26f81c8 ffff8814e26f81e0 0000000000238000 00000000000a8000 > >> ffff881374edb880 ffffffff816a8425 ffff8814433d4a80 ffff881374edb8d8 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffff816aaffd>] rwsem_down_read_failed+0xed/0x130 > >> [<ffffffff813ce404>] call_rwsem_down_read_failed+0x14/0x30 > >> DWARF2 unwinder stuck at call_rwsem_down_read_failed+0x14/0x30 > >> > >> Leftover inexact backtrace: > >> > >> [<ffffffff816aa5a7>] ? down_read+0x17/0x20 > >> [<ffffffffc0376cc6>] btrfs_create_dio_extent+0x46/0x1e0 [btrfs] > >> [<ffffffffc0386a68>] btrfs_get_blocks_direct+0x3d8/0x730 [btrfs] > >> [<ffffffffc0378b2e>] ? btrfs_submit_direct+0x1ce/0x740 [btrfs] > >> [<ffffffff8120b2c7>] do_blockdev_direct_IO+0x11f7/0x2bc0 > >> [<ffffffffc0386690>] ? btrfs_page_exists_in_range+0xe0/0xe0 [btrfs] > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffff8120ccd3>] __blockdev_direct_IO+0x43/0x50 > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffffc0377e11>] btrfs_direct_IO+0x1d1/0x380 [btrfs] > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffff8115656a>] generic_file_direct_write+0xaa/0x170 > >> [<ffffffffc038d4de>] btrfs_file_write_iter+0x2ae/0x560 [btrfs] > >> [<ffffffff810f73c1>] ? futex_wake+0x81/0x150 > >> [<ffffffff811cedd4>] new_sync_write+0x84/0xb0 > >> [<ffffffff811cee26>] __vfs_write+0x26/0x40 > >> [<ffffffff811cf419>] vfs_write+0xa9/0x190 > >> [<ffffffff810026af>] ? enter_from_user_mode+0x1f/0x50 > >> [<ffffffff811d027b>] SyS_pwrite64+0x6b/0xa0 > >> [<ffffffff81002b20>] ? syscall_return_slowpath+0xb0/0x130 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> INFO: task btrfs-transacti:604 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> btrfs-transacti D ffff8814e78cbe00 0 604 2 0x00080000 > >> ffff8814e78cbe00 ffff88017367a540 ffff8814e2f88000 ffff8814e78cc000 > >> ffff8814e78cbe38 ffff88123616c510 ffff8814e24c81f0 ffff88153fb0a000 > >> ffff8814e78cbe18 ffffffff816a8425 ffff8814e63165a0 ffff8814e78cbe88 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03751a5>] btrfs_commit_transaction+0x275/0xa50 [btrfs] > >> [<ffffffffc036fdd6>] transaction_kthread+0x1d6/0x200 [btrfs] > >> [<ffffffff810a0cbb>] kthread+0xdb/0x100 > >> [<ffffffff816ac84f>] ret_from_fork+0x3f/0x70 > >> DWARF2 unwinder stuck at ret_from_fork+0x3f/0x70 > >> > >> Leftover inexact backtrace: > >> > >> [<ffffffff810a0be0>] ? kthread_park+0x60/0x60 > >> INFO: task mysqld:1977 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff88142ef1bcf8 0 1977 1 0x00080000 > >> ffff88142ef1bcf8 ffffffff81e0f500 ffff8814dc2c4a80 ffff88142ef1c000 > >> ffff8814e32ed298 ffff8814e32ed2c0 ffff88110aa9a000 ffff8814e32ed000 > >> ffff88142ef1bd10 ffffffff816a8425 ffff8814e32ed000 ffff88142ef1bd60 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03b38a2>] wait_for_writer+0xa2/0xb0 [btrfs] > >> [<ffffffffc03bb439>] btrfs_sync_log+0xe9/0xa00 [btrfs] > >> [<ffffffffc038d1bf>] btrfs_sync_file+0x35f/0x3d0 [btrfs] > >> [<ffffffff8120055d>] vfs_fsync_range+0x3d/0xb0 > >> [<ffffffff8120062d>] do_fsync+0x3d/0x70 > >> [<ffffffff812008a0>] SyS_fsync+0x10/0x20 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x71 > >> > >> Leftover inexact backtrace: > >> > >> INFO: task mysqld:3249 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff881475fdfa40 0 3249 1 0x00080000 > >> ffff881475fdfa40 ffff88017367ca80 ffff8814433d2540 ffff881475fe0000 > >> ffff88040da39ba0 0000000000230000 ffff88040da39c20 0000000000238000 > >> ffff881475fdfa58 ffffffff816a8425 0000000000008000 ffff881475fdfb18 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03b4cb7>] > >> wait_ordered_extents.isra.18.constprop.23+0x147/0x3d0 [btrfs] > >> [<ffffffffc03b5182>] btrfs_log_changed_extents+0x242/0x610 [btrfs] > >> [<ffffffffc03ba6a4>] btrfs_log_inode+0x874/0xb80 [btrfs] > >> [<ffffffffc03bac6c>] btrfs_log_inode_parent+0x22c/0x910 [btrfs] > >> [<ffffffffc03bc292>] btrfs_log_dentry_safe+0x62/0x80 [btrfs] > >> [<ffffffffc038d0ec>] btrfs_sync_file+0x28c/0x3d0 [btrfs] > >> [<ffffffff8120055d>] vfs_fsync_range+0x3d/0xb0 > >> [<ffffffff8120062d>] do_fsync+0x3d/0x70 > >> [<ffffffff812008a0>] SyS_fsync+0x10/0x20 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x71 > >> > >> Leftover inexact backtrace: > >> > >> INFO: task mysqld:3250 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff881374edb868 0 3250 1 0x00080000 > >> ffff881374edb868 ffff8801736b2540 ffff8814433d4a80 ffff881374edc000 > >> ffff8814e26f81c8 ffff8814e26f81e0 0000000000238000 00000000000a8000 > >> ffff881374edb880 ffffffff816a8425 ffff8814433d4a80 ffff881374edb8d8 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffff816aaffd>] rwsem_down_read_failed+0xed/0x130 > >> [<ffffffff813ce404>] call_rwsem_down_read_failed+0x14/0x30 > >> DWARF2 unwinder stuck at call_rwsem_down_read_failed+0x14/0x30 > >> > >> Leftover inexact backtrace: > >> > >> [<ffffffff816aa5a7>] ? down_read+0x17/0x20 > >> [<ffffffffc0376cc6>] btrfs_create_dio_extent+0x46/0x1e0 [btrfs] > >> [<ffffffffc0386a68>] btrfs_get_blocks_direct+0x3d8/0x730 [btrfs] > >> [<ffffffffc0378b2e>] ? btrfs_submit_direct+0x1ce/0x740 [btrfs] > >> [<ffffffff8120b2c7>] do_blockdev_direct_IO+0x11f7/0x2bc0 > >> [<ffffffffc0386690>] ? btrfs_page_exists_in_range+0xe0/0xe0 [btrfs] > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffff8120ccd3>] __blockdev_direct_IO+0x43/0x50 > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffffc0377e11>] btrfs_direct_IO+0x1d1/0x380 [btrfs] > >> [<ffffffffc0378960>] ? btrfs_getattr+0xa0/0xa0 [btrfs] > >> [<ffffffff8115656a>] generic_file_direct_write+0xaa/0x170 > >> [<ffffffffc038d4de>] btrfs_file_write_iter+0x2ae/0x560 [btrfs] > >> [<ffffffff810f73c1>] ? futex_wake+0x81/0x150 > >> [<ffffffff811cedd4>] new_sync_write+0x84/0xb0 > >> [<ffffffff811cee26>] __vfs_write+0x26/0x40 > >> [<ffffffff811cf419>] vfs_write+0xa9/0x190 > >> [<ffffffff810026af>] ? enter_from_user_mode+0x1f/0x50 > >> [<ffffffff811d027b>] SyS_pwrite64+0x6b/0xa0 > >> [<ffffffff81002b20>] ? syscall_return_slowpath+0xb0/0x130 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> INFO: task btrfs-transacti:604 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> btrfs-transacti D ffff8814e78cbe00 0 604 2 0x00080000 > >> ffff8814e78cbe00 ffff88017367a540 ffff8814e2f88000 ffff8814e78cc000 > >> ffff8814e78cbe38 ffff88123616c510 ffff8814e24c81f0 ffff88153fb0a000 > >> ffff8814e78cbe18 ffffffff816a8425 ffff8814e63165a0 ffff8814e78cbe88 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03751a5>] btrfs_commit_transaction+0x275/0xa50 [btrfs] > >> [<ffffffffc036fdd6>] transaction_kthread+0x1d6/0x200 [btrfs] > >> [<ffffffff810a0cbb>] kthread+0xdb/0x100 > >> [<ffffffff816ac84f>] ret_from_fork+0x3f/0x70 > >> DWARF2 unwinder stuck at ret_from_fork+0x3f/0x70 > >> > >> Leftover inexact backtrace: > >> > >> [<ffffffff810a0be0>] ? kthread_park+0x60/0x60 > >> INFO: task mysqld:1977 blocked for more than 120 seconds. > >> Not tainted 4.4.34 #1 > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> mysqld D ffff88142ef1bcf8 0 1977 1 0x00080000 > >> ffff88142ef1bcf8 ffffffff81e0f500 ffff8814dc2c4a80 ffff88142ef1c000 > >> ffff8814e32ed298 ffff8814e32ed2c0 ffff88110aa9a000 ffff8814e32ed000 > >> ffff88142ef1bd10 ffffffff816a8425 ffff8814e32ed000 ffff88142ef1bd60 > >> Call Trace: > >> [<ffffffff816a8425>] schedule+0x35/0x80 > >> [<ffffffffc03b38a2>] wait_for_writer+0xa2/0xb0 [btrfs] > >> [<ffffffffc03bb439>] btrfs_sync_log+0xe9/0xa00 [btrfs] > >> [<ffffffffc038d1bf>] btrfs_sync_file+0x35f/0x3d0 [btrfs] > >> [<ffffffff8120055d>] vfs_fsync_range+0x3d/0xb0 > >> [<ffffffff8120062d>] do_fsync+0x3d/0x70 > >> [<ffffffff812008a0>] SyS_fsync+0x10/0x20 > >> [<ffffffff816ac4ee>] entry_SYSCALL_64_fastpath+0x12/0x71 > >> DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x71 > >> > >> Leftover inexact backtrace: > >> > >> Greets, > >> Stefan > >> > >> > > >> > Signed-off-by: Liu Bo <bo.li....@oracle.com> > >> > Reviewed-by: Chris Mason <c...@fb.com> > >> > --- > >> > fs/btrfs/inode.c | 8 +++++--- > >> > 1 file changed, 5 insertions(+), 3 deletions(-) > >> > > >> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > >> > index 2b790bd..48e9356 100644 > >> > --- a/fs/btrfs/inode.c > >> > +++ b/fs/btrfs/inode.c > >> > @@ -7783,10 +7783,12 @@ static int btrfs_get_blocks_direct(struct inode > >> > *inode, sector_t iblock, > >> > } > >> > > >> > /* > >> > - * this will cow the extent, reset the len in case we changed > >> > - * it above > >> > + * this will cow the extent, if em is within [start, len], then > >> > + * probably we've found a preallocated/existing extent, let's > >> > + * give it a chance to use preallocated space. > >> > */ > >> > - len = bh_result->b_size; > >> > + len = min_t(u64, bh_result->b_size, em->len - (start - em->start)); > >> > + len = ALIGN(len, root->sectorsize); > >> > free_extent_map(em); > >> > em = btrfs_new_extent_direct(inode, start, len); > >> > if (IS_ERR(em)) { > >> > > > > > -- > Filipe David Manana, > > "People will forget what you said, > people will forget what you did, > but people will never forget how you made them feel." > -- > 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 -- 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