Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
At 02/20/2017 09:43 PM, Filipe Manana wrote: On Mon, Feb 20, 2017 at 12:31 AM, Qu Wenruowrote: At 02/17/2017 11:25 PM, Filipe Manana wrote: On Fri, Feb 17, 2017 at 12:37 AM, Qu Wenruo wrote: In case of an error the endio handler is called only for the first page, and not for whole range for which one or more ordered extents were created. So the ordered extents will be around forever. That's the same thing I'm trying to fix. While I'm asking the reason the cleanup previously created ordered extent, which didn't encounter any error. Any error in the loop requires cleaning up previously created ordered extents, because if that function returns an error no bio is submitted and therefore the ordered extents won't be removed, except for the case where only one ordered extent is created and the delalloc range is a single page. Or is this a designed behavior for things like fsync? Success for all or failure if any fails? This is unrelated to fsync. It's about leaving ordered extents which can make any task get them and hang on them forever. However in the case of btrfs_reloc_clone_csum(), if it fails, there is only one ordered extent really needs to clean. The problem is more generic and you can forget about btrfs_reloc_clone_csum(). It's about the delalloc callback returning an error and one or more ordered extents were created by past iterations of the loop before the error happened. While the only possible problem we can hit after submitting an ordered extent is btrfs_reloc_clone_csum(). Previously created ordered extent can finish without problem, so we only need to clean the last created one, and no need to cleanup all ordered extent that it created. For a more specific example of this case: We are relocating one data block group, whose size is 1G, containing 8 128M file extents. For run_delalloc_nocow(), it's called on root DATA_RELOC inode 257, range is [0,1G), And for first loop, it handles the first [0, 128M) without problem. 1st ordered extent is submitted and can finish even before submitting 2nd ordered extent. The ordered extent is submitted but not a bio for it. It's when the bio completes (writeback finishes) that the endio callback is invoked, which wakes up every task waiting on the ordered extent, sets IO errors bit if needed, removes the ordered extent, etc. Then when we are submitting 2nd ordered extent, ranged from [128M, 256M), btrfs_reloc_clone_csum() fails. we must cleanup at least 2nd ordered extent or it will hang forever. If I understand your right, you mean we must cleanup all ordered extent in the range [0, 1G). Yes. My point is, since 1st ordered extent can be submitted and finished before 2nd ordered extent submission without problem, I didn't see the point to cleanup 1st ordered extent and non-exist 3rd~8th ordered extent. As said before in this reply, if the delalloc callback (cow_file_range, run_dellaloc_nocow) returns an error, no bios are submitted for any ordered extents it might have created before an error happened. Check __extent_writepage() - it calls writepage_delalloc() which calls our delalloc callback, and if that returns an error, it won't call __extent_writepage_io(), which is what submits bios. Or I missed or misunderstand something else? You missed a lot of things I suppose, namely that bios aren't submitted if the dealloc function returns an error. That's the point. I misunderstand the bio submission timing, so in that case you're right about cleanup the whole range. I'll update the patch to address it. Thanks, Qu Honestly I don't know how to explain things better to you, and was hopping this was easier to understand using the direct IO write error path as an example. thanks Thanks, Qu thanks Thanks, Qu In that case, since we haven't unlock pages/extent, there will no race nor new ordered extent, and we are ensured to have only one ordered extent need cleanup. Also, for any created ordered extent, you want to set the bit BTRFS_ORDERED_IOERR on it before removing it, since there might be concurrent tasks waiting for it that do error handling (like an fsync, since when running delalloc the inode isn't locked). Fsync is not affected IIRC, as btrfs_reloc_clone_csum() is only called for DATA_RELOC tree inode, which we don't call fsync on it. Look at the direct IO write path error handling and btrfs_endio_direct_write_update_ordered() for a very similar scenario. And the same problem happens in the cow case (inode.c:cow_file_range()). BTW, I have already done it in cow_file_range(), check the beginning lines of inode.c of this patch. Indeed. I missed it. Thanks. Thanks, Qu Thanks. + } btrfs_free_path(path); return ret; } diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 041c3326d109..dba1cf3464a7 100644 --- a/fs/btrfs/ordered-data.c +++
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
On Mon, Feb 20, 2017 at 12:31 AM, Qu Wenruowrote: > > > At 02/17/2017 11:25 PM, Filipe Manana wrote: >> >> On Fri, Feb 17, 2017 at 12:37 AM, Qu Wenruo >> wrote: >>> >>> >>> >>> At 02/16/2017 06:03 PM, Filipe Manana wrote: On Thu, Feb 16, 2017 at 12:39 AM, Qu Wenruo wrote: > > > > > At 02/15/2017 11:59 PM, Filipe Manana wrote: >> >> >> >> On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruo >> wrote: >>> >>> >>> >>> If run btrfs/125 with nospace_cache or space_cache=v2 mount option, >>> btrfs will block with the following backtrace: >>> >>> Call Trace: >>> __schedule+0x2d4/0xae0 >>> schedule+0x3d/0x90 >>> btrfs_start_ordered_extent+0x160/0x200 [btrfs] >>> ? wake_atomic_t_function+0x60/0x60 >>> btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] >>> btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] >>> btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] >>> process_one_work+0x2af/0x720 >>> ? process_one_work+0x22b/0x720 >>> worker_thread+0x4b/0x4f0 >>> kthread+0x10f/0x150 >>> ? process_one_work+0x720/0x720 >>> ? kthread_create_on_node+0x40/0x40 >>> ret_from_fork+0x2e/0x40 >>> >>> The direct cause is the error handler in run_delalloc_nocow() doesn't >>> handle error from btrfs_reloc_clone_csums() well. >>> >>> The related part call path will be: >>> __extent_writepage >>> |- writepage_delalloc() >>> | |- run_delalloc_range() >>> | |- run_delalloc_nocow() >>> ||- btrfs_add_ordered_extent() >>> || Now one ordered extent for file range, e.g [0, 1M) is >>> inserted >>> || >>> ||- btrfs_reloc_clone_csums() >>> || Fails with -EIO, as RAID5/6 doesn't repair some csum tree >>> || blocks >>> || >>> ||- extent_clear_unlock_delalloc() >>> | Error routine, unlock and clear page DIRTY, end page >>> writeback >>> | So the remaining 255 pages will not go through writeback >>> | >>> |- __extent_writepage_io() >>>|- writepage_end_io_hook() >>> |- btrfs_dev_test_ordered_pending() >>> Reduce ordered_extent->bytes_left by 4K. >>> Still have (1M - 4K) to finish. >>> >>> While the remaining 255 pages will not go through IO nor trigger >>> writepage_end_io_hook(), the ordered extent for [0, 1M) will >>> never finish, and blocking current transaction forever. >>> >>> Although the root cause is still in RAID5/6, it won't hurt to fix the >>> error routine first. >>> >>> This patch will cleanup the ordered extent in error routine, so at >>> least >>> we won't cause deadlock. >>> >>> Signed-off-by: Qu Wenruo >>> --- >>> fs/btrfs/extent_io.c| 1 - >>> fs/btrfs/inode.c| 10 -- >>> fs/btrfs/ordered-data.c | 25 + >>> fs/btrfs/ordered-data.h | 10 ++ >>> 4 files changed, 43 insertions(+), 3 deletions(-) >>> >>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>> index 4ac383a3a649..a14d1b0840c5 100644 >>> --- a/fs/btrfs/extent_io.c >>> +++ b/fs/btrfs/extent_io.c >>> @@ -3258,7 +3258,6 @@ static noinline_for_stack int >>> writepage_delalloc(struct inode *inode, >>>delalloc_end, >>>_started, >>>nr_written); >>> - /* File system has been set read-only */ >>> if (ret) { >>> SetPageError(page); >>> /* fill_delalloc should be return < 0 for >>> error >>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >>> index 1e861a063721..3c3ade58afd7 100644 >>> --- a/fs/btrfs/inode.c >>> +++ b/fs/btrfs/inode.c >>> @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct >>> inode >>> *inode, >>> BTRFS_DATA_RELOC_TREE_OBJECTID) { >>> ret = btrfs_reloc_clone_csums(inode, start, >>> >>> cur_alloc_size); >>> - if (ret) >>> + if (ret) { >>> + btrfs_clean_ordered_extent(inode, >>> start, >>> + ram_size); >>> goto out_drop_extent_cache; >>> + } >>> } >>> >>> btrfs_dec_block_group_reservations(fs_info, >>> ins.objectid); >>> @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct >>> inode >>>
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
At 02/17/2017 11:25 PM, Filipe Manana wrote: On Fri, Feb 17, 2017 at 12:37 AM, Qu Wenruowrote: At 02/16/2017 06:03 PM, Filipe Manana wrote: On Thu, Feb 16, 2017 at 12:39 AM, Qu Wenruo wrote: At 02/15/2017 11:59 PM, Filipe Manana wrote: On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruo wrote: If run btrfs/125 with nospace_cache or space_cache=v2 mount option, btrfs will block with the following backtrace: Call Trace: __schedule+0x2d4/0xae0 schedule+0x3d/0x90 btrfs_start_ordered_extent+0x160/0x200 [btrfs] ? wake_atomic_t_function+0x60/0x60 btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 The direct cause is the error handler in run_delalloc_nocow() doesn't handle error from btrfs_reloc_clone_csums() well. The related part call path will be: __extent_writepage |- writepage_delalloc() | |- run_delalloc_range() | |- run_delalloc_nocow() ||- btrfs_add_ordered_extent() || Now one ordered extent for file range, e.g [0, 1M) is inserted || ||- btrfs_reloc_clone_csums() || Fails with -EIO, as RAID5/6 doesn't repair some csum tree || blocks || ||- extent_clear_unlock_delalloc() | Error routine, unlock and clear page DIRTY, end page writeback | So the remaining 255 pages will not go through writeback | |- __extent_writepage_io() |- writepage_end_io_hook() |- btrfs_dev_test_ordered_pending() Reduce ordered_extent->bytes_left by 4K. Still have (1M - 4K) to finish. While the remaining 255 pages will not go through IO nor trigger writepage_end_io_hook(), the ordered extent for [0, 1M) will never finish, and blocking current transaction forever. Although the root cause is still in RAID5/6, it won't hurt to fix the error routine first. This patch will cleanup the ordered extent in error routine, so at least we won't cause deadlock. Signed-off-by: Qu Wenruo --- fs/btrfs/extent_io.c| 1 - fs/btrfs/inode.c| 10 -- fs/btrfs/ordered-data.c | 25 + fs/btrfs/ordered-data.h | 10 ++ 4 files changed, 43 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4ac383a3a649..a14d1b0840c5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode, delalloc_end, _started, nr_written); - /* File system has been set read-only */ if (ret) { SetPageError(page); /* fill_delalloc should be return < 0 for error diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e861a063721..3c3ade58afd7 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode *inode, BTRFS_DATA_RELOC_TREE_OBJECTID) { ret = btrfs_reloc_clone_csums(inode, start, cur_alloc_size); - if (ret) + if (ret) { + btrfs_clean_ordered_extent(inode, start, + ram_size); goto out_drop_extent_cache; + } } btrfs_dec_block_group_reservations(fs_info, ins.objectid); @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, if (!ret) ret = err; - if (ret && cur_offset < end) + if (ret && cur_offset < end) { extent_clear_unlock_delalloc(inode, cur_offset, end, end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG | @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode *inode, PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + btrfs_clean_ordered_extent(inode, cur_offset, + end - cur_offset + 1); So this is partially correct only. First here you can have 0, 1 or more ordered extents that were created in the while loop. So your new function must find and process all ordered extents within the
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
On Fri, Feb 17, 2017 at 12:37 AM, Qu Wenruowrote: > > > At 02/16/2017 06:03 PM, Filipe Manana wrote: >> >> On Thu, Feb 16, 2017 at 12:39 AM, Qu Wenruo >> wrote: >>> >>> >>> >>> At 02/15/2017 11:59 PM, Filipe Manana wrote: On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruo wrote: > > > If run btrfs/125 with nospace_cache or space_cache=v2 mount option, > btrfs will block with the following backtrace: > > Call Trace: > __schedule+0x2d4/0xae0 > schedule+0x3d/0x90 > btrfs_start_ordered_extent+0x160/0x200 [btrfs] > ? wake_atomic_t_function+0x60/0x60 > btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] > btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] > btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] > process_one_work+0x2af/0x720 > ? process_one_work+0x22b/0x720 > worker_thread+0x4b/0x4f0 > kthread+0x10f/0x150 > ? process_one_work+0x720/0x720 > ? kthread_create_on_node+0x40/0x40 > ret_from_fork+0x2e/0x40 > > The direct cause is the error handler in run_delalloc_nocow() doesn't > handle error from btrfs_reloc_clone_csums() well. > > The related part call path will be: > __extent_writepage > |- writepage_delalloc() > | |- run_delalloc_range() > | |- run_delalloc_nocow() > ||- btrfs_add_ordered_extent() > || Now one ordered extent for file range, e.g [0, 1M) is > inserted > || > ||- btrfs_reloc_clone_csums() > || Fails with -EIO, as RAID5/6 doesn't repair some csum tree > || blocks > || > ||- extent_clear_unlock_delalloc() > | Error routine, unlock and clear page DIRTY, end page > writeback > | So the remaining 255 pages will not go through writeback > | > |- __extent_writepage_io() >|- writepage_end_io_hook() > |- btrfs_dev_test_ordered_pending() > Reduce ordered_extent->bytes_left by 4K. > Still have (1M - 4K) to finish. > > While the remaining 255 pages will not go through IO nor trigger > writepage_end_io_hook(), the ordered extent for [0, 1M) will > never finish, and blocking current transaction forever. > > Although the root cause is still in RAID5/6, it won't hurt to fix the > error routine first. > > This patch will cleanup the ordered extent in error routine, so at > least > we won't cause deadlock. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/extent_io.c| 1 - > fs/btrfs/inode.c| 10 -- > fs/btrfs/ordered-data.c | 25 + > fs/btrfs/ordered-data.h | 10 ++ > 4 files changed, 43 insertions(+), 3 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 4ac383a3a649..a14d1b0840c5 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -3258,7 +3258,6 @@ static noinline_for_stack int > writepage_delalloc(struct inode *inode, >delalloc_end, >_started, >nr_written); > - /* File system has been set read-only */ > if (ret) { > SetPageError(page); > /* fill_delalloc should be return < 0 for error > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 1e861a063721..3c3ade58afd7 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode > *inode, > BTRFS_DATA_RELOC_TREE_OBJECTID) { > ret = btrfs_reloc_clone_csums(inode, start, > cur_alloc_size); > - if (ret) > + if (ret) { > + btrfs_clean_ordered_extent(inode, > start, > + ram_size); > goto out_drop_extent_cache; > + } > } > > btrfs_dec_block_group_reservations(fs_info, > ins.objectid); > @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct > inode > *inode, > if (!ret) > ret = err; > > - if (ret && cur_offset < end) > + if (ret && cur_offset < end) { > extent_clear_unlock_delalloc(inode, cur_offset, end, > end, > locked_page, EXTENT_LOCKED > | >
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
At 02/16/2017 06:03 PM, Filipe Manana wrote: On Thu, Feb 16, 2017 at 12:39 AM, Qu Wenruowrote: At 02/15/2017 11:59 PM, Filipe Manana wrote: On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruo wrote: If run btrfs/125 with nospace_cache or space_cache=v2 mount option, btrfs will block with the following backtrace: Call Trace: __schedule+0x2d4/0xae0 schedule+0x3d/0x90 btrfs_start_ordered_extent+0x160/0x200 [btrfs] ? wake_atomic_t_function+0x60/0x60 btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 The direct cause is the error handler in run_delalloc_nocow() doesn't handle error from btrfs_reloc_clone_csums() well. The related part call path will be: __extent_writepage |- writepage_delalloc() | |- run_delalloc_range() | |- run_delalloc_nocow() ||- btrfs_add_ordered_extent() || Now one ordered extent for file range, e.g [0, 1M) is inserted || ||- btrfs_reloc_clone_csums() || Fails with -EIO, as RAID5/6 doesn't repair some csum tree || blocks || ||- extent_clear_unlock_delalloc() | Error routine, unlock and clear page DIRTY, end page writeback | So the remaining 255 pages will not go through writeback | |- __extent_writepage_io() |- writepage_end_io_hook() |- btrfs_dev_test_ordered_pending() Reduce ordered_extent->bytes_left by 4K. Still have (1M - 4K) to finish. While the remaining 255 pages will not go through IO nor trigger writepage_end_io_hook(), the ordered extent for [0, 1M) will never finish, and blocking current transaction forever. Although the root cause is still in RAID5/6, it won't hurt to fix the error routine first. This patch will cleanup the ordered extent in error routine, so at least we won't cause deadlock. Signed-off-by: Qu Wenruo --- fs/btrfs/extent_io.c| 1 - fs/btrfs/inode.c| 10 -- fs/btrfs/ordered-data.c | 25 + fs/btrfs/ordered-data.h | 10 ++ 4 files changed, 43 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4ac383a3a649..a14d1b0840c5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode, delalloc_end, _started, nr_written); - /* File system has been set read-only */ if (ret) { SetPageError(page); /* fill_delalloc should be return < 0 for error diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e861a063721..3c3ade58afd7 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode *inode, BTRFS_DATA_RELOC_TREE_OBJECTID) { ret = btrfs_reloc_clone_csums(inode, start, cur_alloc_size); - if (ret) + if (ret) { + btrfs_clean_ordered_extent(inode, start, + ram_size); goto out_drop_extent_cache; + } } btrfs_dec_block_group_reservations(fs_info, ins.objectid); @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, if (!ret) ret = err; - if (ret && cur_offset < end) + if (ret && cur_offset < end) { extent_clear_unlock_delalloc(inode, cur_offset, end, end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG | @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode *inode, PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + btrfs_clean_ordered_extent(inode, cur_offset, + end - cur_offset + 1); So this is partially correct only. First here you can have 0, 1 or more ordered extents that were created in the while loop. So your new function must find and process all ordered extents within the delalloc range and not just the last one that was created. OK, I found that only btrfs_reloc_clone_csums() will need to cleanup
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
On Thu, Feb 16, 2017 at 12:39 AM, Qu Wenruowrote: > > > At 02/15/2017 11:59 PM, Filipe Manana wrote: >> >> On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruo >> wrote: >>> >>> If run btrfs/125 with nospace_cache or space_cache=v2 mount option, >>> btrfs will block with the following backtrace: >>> >>> Call Trace: >>> __schedule+0x2d4/0xae0 >>> schedule+0x3d/0x90 >>> btrfs_start_ordered_extent+0x160/0x200 [btrfs] >>> ? wake_atomic_t_function+0x60/0x60 >>> btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] >>> btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] >>> btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] >>> process_one_work+0x2af/0x720 >>> ? process_one_work+0x22b/0x720 >>> worker_thread+0x4b/0x4f0 >>> kthread+0x10f/0x150 >>> ? process_one_work+0x720/0x720 >>> ? kthread_create_on_node+0x40/0x40 >>> ret_from_fork+0x2e/0x40 >>> >>> The direct cause is the error handler in run_delalloc_nocow() doesn't >>> handle error from btrfs_reloc_clone_csums() well. >>> >>> The related part call path will be: >>> __extent_writepage >>> |- writepage_delalloc() >>> | |- run_delalloc_range() >>> | |- run_delalloc_nocow() >>> ||- btrfs_add_ordered_extent() >>> || Now one ordered extent for file range, e.g [0, 1M) is >>> inserted >>> || >>> ||- btrfs_reloc_clone_csums() >>> || Fails with -EIO, as RAID5/6 doesn't repair some csum tree >>> || blocks >>> || >>> ||- extent_clear_unlock_delalloc() >>> | Error routine, unlock and clear page DIRTY, end page >>> writeback >>> | So the remaining 255 pages will not go through writeback >>> | >>> |- __extent_writepage_io() >>>|- writepage_end_io_hook() >>> |- btrfs_dev_test_ordered_pending() >>> Reduce ordered_extent->bytes_left by 4K. >>> Still have (1M - 4K) to finish. >>> >>> While the remaining 255 pages will not go through IO nor trigger >>> writepage_end_io_hook(), the ordered extent for [0, 1M) will >>> never finish, and blocking current transaction forever. >>> >>> Although the root cause is still in RAID5/6, it won't hurt to fix the >>> error routine first. >>> >>> This patch will cleanup the ordered extent in error routine, so at least >>> we won't cause deadlock. >>> >>> Signed-off-by: Qu Wenruo >>> --- >>> fs/btrfs/extent_io.c| 1 - >>> fs/btrfs/inode.c| 10 -- >>> fs/btrfs/ordered-data.c | 25 + >>> fs/btrfs/ordered-data.h | 10 ++ >>> 4 files changed, 43 insertions(+), 3 deletions(-) >>> >>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>> index 4ac383a3a649..a14d1b0840c5 100644 >>> --- a/fs/btrfs/extent_io.c >>> +++ b/fs/btrfs/extent_io.c >>> @@ -3258,7 +3258,6 @@ static noinline_for_stack int >>> writepage_delalloc(struct inode *inode, >>>delalloc_end, >>>_started, >>>nr_written); >>> - /* File system has been set read-only */ >>> if (ret) { >>> SetPageError(page); >>> /* fill_delalloc should be return < 0 for error >>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >>> index 1e861a063721..3c3ade58afd7 100644 >>> --- a/fs/btrfs/inode.c >>> +++ b/fs/btrfs/inode.c >>> @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode >>> *inode, >>> BTRFS_DATA_RELOC_TREE_OBJECTID) { >>> ret = btrfs_reloc_clone_csums(inode, start, >>> cur_alloc_size); >>> - if (ret) >>> + if (ret) { >>> + btrfs_clean_ordered_extent(inode, start, >>> + ram_size); >>> goto out_drop_extent_cache; >>> + } >>> } >>> >>> btrfs_dec_block_group_reservations(fs_info, >>> ins.objectid); >>> @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode >>> *inode, >>> if (!ret) >>> ret = err; >>> >>> - if (ret && cur_offset < end) >>> + if (ret && cur_offset < end) { >>> extent_clear_unlock_delalloc(inode, cur_offset, end, end, >>> locked_page, EXTENT_LOCKED | >>> EXTENT_DELALLOC | >>> EXTENT_DEFRAG | >>> @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode >>> *inode, >>> PAGE_CLEAR_DIRTY | >>> PAGE_SET_WRITEBACK | >>> PAGE_END_WRITEBACK); >>> + btrfs_clean_ordered_extent(inode,
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
At 02/15/2017 11:59 PM, Filipe Manana wrote: On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruowrote: If run btrfs/125 with nospace_cache or space_cache=v2 mount option, btrfs will block with the following backtrace: Call Trace: __schedule+0x2d4/0xae0 schedule+0x3d/0x90 btrfs_start_ordered_extent+0x160/0x200 [btrfs] ? wake_atomic_t_function+0x60/0x60 btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 The direct cause is the error handler in run_delalloc_nocow() doesn't handle error from btrfs_reloc_clone_csums() well. The related part call path will be: __extent_writepage |- writepage_delalloc() | |- run_delalloc_range() | |- run_delalloc_nocow() ||- btrfs_add_ordered_extent() || Now one ordered extent for file range, e.g [0, 1M) is inserted || ||- btrfs_reloc_clone_csums() || Fails with -EIO, as RAID5/6 doesn't repair some csum tree || blocks || ||- extent_clear_unlock_delalloc() | Error routine, unlock and clear page DIRTY, end page writeback | So the remaining 255 pages will not go through writeback | |- __extent_writepage_io() |- writepage_end_io_hook() |- btrfs_dev_test_ordered_pending() Reduce ordered_extent->bytes_left by 4K. Still have (1M - 4K) to finish. While the remaining 255 pages will not go through IO nor trigger writepage_end_io_hook(), the ordered extent for [0, 1M) will never finish, and blocking current transaction forever. Although the root cause is still in RAID5/6, it won't hurt to fix the error routine first. This patch will cleanup the ordered extent in error routine, so at least we won't cause deadlock. Signed-off-by: Qu Wenruo --- fs/btrfs/extent_io.c| 1 - fs/btrfs/inode.c| 10 -- fs/btrfs/ordered-data.c | 25 + fs/btrfs/ordered-data.h | 10 ++ 4 files changed, 43 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4ac383a3a649..a14d1b0840c5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode, delalloc_end, _started, nr_written); - /* File system has been set read-only */ if (ret) { SetPageError(page); /* fill_delalloc should be return < 0 for error diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e861a063721..3c3ade58afd7 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode *inode, BTRFS_DATA_RELOC_TREE_OBJECTID) { ret = btrfs_reloc_clone_csums(inode, start, cur_alloc_size); - if (ret) + if (ret) { + btrfs_clean_ordered_extent(inode, start, + ram_size); goto out_drop_extent_cache; + } } btrfs_dec_block_group_reservations(fs_info, ins.objectid); @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, if (!ret) ret = err; - if (ret && cur_offset < end) + if (ret && cur_offset < end) { extent_clear_unlock_delalloc(inode, cur_offset, end, end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG | @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode *inode, PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + btrfs_clean_ordered_extent(inode, cur_offset, + end - cur_offset + 1); So this is partially correct only. First here you can have 0, 1 or more ordered extents that were created in the while loop. So your new function must find and process all ordered extents within the delalloc range and not just the last one that was created. OK, I found that only btrfs_reloc_clone_csums() will need to cleanup ordered extent, and there is no other case which can cause error after adding ordered extent. So what about moving the
Re: [PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
On Wed, Feb 15, 2017 at 8:49 AM, Qu Wenruowrote: > If run btrfs/125 with nospace_cache or space_cache=v2 mount option, > btrfs will block with the following backtrace: > > Call Trace: > __schedule+0x2d4/0xae0 > schedule+0x3d/0x90 > btrfs_start_ordered_extent+0x160/0x200 [btrfs] > ? wake_atomic_t_function+0x60/0x60 > btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] > btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] > btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] > process_one_work+0x2af/0x720 > ? process_one_work+0x22b/0x720 > worker_thread+0x4b/0x4f0 > kthread+0x10f/0x150 > ? process_one_work+0x720/0x720 > ? kthread_create_on_node+0x40/0x40 > ret_from_fork+0x2e/0x40 > > The direct cause is the error handler in run_delalloc_nocow() doesn't > handle error from btrfs_reloc_clone_csums() well. > > The related part call path will be: > __extent_writepage > |- writepage_delalloc() > | |- run_delalloc_range() > | |- run_delalloc_nocow() > ||- btrfs_add_ordered_extent() > || Now one ordered extent for file range, e.g [0, 1M) is inserted > || > ||- btrfs_reloc_clone_csums() > || Fails with -EIO, as RAID5/6 doesn't repair some csum tree > || blocks > || > ||- extent_clear_unlock_delalloc() > | Error routine, unlock and clear page DIRTY, end page writeback > | So the remaining 255 pages will not go through writeback > | > |- __extent_writepage_io() >|- writepage_end_io_hook() > |- btrfs_dev_test_ordered_pending() > Reduce ordered_extent->bytes_left by 4K. > Still have (1M - 4K) to finish. > > While the remaining 255 pages will not go through IO nor trigger > writepage_end_io_hook(), the ordered extent for [0, 1M) will > never finish, and blocking current transaction forever. > > Although the root cause is still in RAID5/6, it won't hurt to fix the > error routine first. > > This patch will cleanup the ordered extent in error routine, so at least > we won't cause deadlock. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/extent_io.c| 1 - > fs/btrfs/inode.c| 10 -- > fs/btrfs/ordered-data.c | 25 + > fs/btrfs/ordered-data.h | 10 ++ > 4 files changed, 43 insertions(+), 3 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 4ac383a3a649..a14d1b0840c5 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct > inode *inode, >delalloc_end, >_started, >nr_written); > - /* File system has been set read-only */ > if (ret) { > SetPageError(page); > /* fill_delalloc should be return < 0 for error > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 1e861a063721..3c3ade58afd7 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode *inode, > BTRFS_DATA_RELOC_TREE_OBJECTID) { > ret = btrfs_reloc_clone_csums(inode, start, > cur_alloc_size); > - if (ret) > + if (ret) { > + btrfs_clean_ordered_extent(inode, start, > + ram_size); > goto out_drop_extent_cache; > + } > } > > btrfs_dec_block_group_reservations(fs_info, ins.objectid); > @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode > *inode, > if (!ret) > ret = err; > > - if (ret && cur_offset < end) > + if (ret && cur_offset < end) { > extent_clear_unlock_delalloc(inode, cur_offset, end, end, > locked_page, EXTENT_LOCKED | > EXTENT_DELALLOC | EXTENT_DEFRAG | > @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode > *inode, > PAGE_CLEAR_DIRTY | > PAGE_SET_WRITEBACK | > PAGE_END_WRITEBACK); > + btrfs_clean_ordered_extent(inode, cur_offset, > + end - cur_offset + 1); So this is partially correct only. First here you can have 0, 1 or more ordered extents that were created in the while loop. So your new function must find and process all ordered extents within the delalloc range and not just the last one that was created. Also, for any created ordered extent, you
[PATCH] btrfs: Handle btrfs_reloc_clone_csums error correctly to avoid deadlock
If run btrfs/125 with nospace_cache or space_cache=v2 mount option, btrfs will block with the following backtrace: Call Trace: __schedule+0x2d4/0xae0 schedule+0x3d/0x90 btrfs_start_ordered_extent+0x160/0x200 [btrfs] ? wake_atomic_t_function+0x60/0x60 btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 The direct cause is the error handler in run_delalloc_nocow() doesn't handle error from btrfs_reloc_clone_csums() well. The related part call path will be: __extent_writepage |- writepage_delalloc() | |- run_delalloc_range() | |- run_delalloc_nocow() ||- btrfs_add_ordered_extent() || Now one ordered extent for file range, e.g [0, 1M) is inserted || ||- btrfs_reloc_clone_csums() || Fails with -EIO, as RAID5/6 doesn't repair some csum tree || blocks || ||- extent_clear_unlock_delalloc() | Error routine, unlock and clear page DIRTY, end page writeback | So the remaining 255 pages will not go through writeback | |- __extent_writepage_io() |- writepage_end_io_hook() |- btrfs_dev_test_ordered_pending() Reduce ordered_extent->bytes_left by 4K. Still have (1M - 4K) to finish. While the remaining 255 pages will not go through IO nor trigger writepage_end_io_hook(), the ordered extent for [0, 1M) will never finish, and blocking current transaction forever. Although the root cause is still in RAID5/6, it won't hurt to fix the error routine first. This patch will cleanup the ordered extent in error routine, so at least we won't cause deadlock. Signed-off-by: Qu Wenruo--- fs/btrfs/extent_io.c| 1 - fs/btrfs/inode.c| 10 -- fs/btrfs/ordered-data.c | 25 + fs/btrfs/ordered-data.h | 10 ++ 4 files changed, 43 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4ac383a3a649..a14d1b0840c5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode, delalloc_end, _started, nr_written); - /* File system has been set read-only */ if (ret) { SetPageError(page); /* fill_delalloc should be return < 0 for error diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e861a063721..3c3ade58afd7 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1052,8 +1052,11 @@ static noinline int cow_file_range(struct inode *inode, BTRFS_DATA_RELOC_TREE_OBJECTID) { ret = btrfs_reloc_clone_csums(inode, start, cur_alloc_size); - if (ret) + if (ret) { + btrfs_clean_ordered_extent(inode, start, + ram_size); goto out_drop_extent_cache; + } } btrfs_dec_block_group_reservations(fs_info, ins.objectid); @@ -1538,7 +1541,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, if (!ret) ret = err; - if (ret && cur_offset < end) + if (ret && cur_offset < end) { extent_clear_unlock_delalloc(inode, cur_offset, end, end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG | @@ -1546,6 +1549,9 @@ static noinline int run_delalloc_nocow(struct inode *inode, PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + btrfs_clean_ordered_extent(inode, cur_offset, + end - cur_offset + 1); + } btrfs_free_path(path); return ret; } diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 041c3326d109..dba1cf3464a7 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -650,6 +650,31 @@ void btrfs_remove_ordered_extent(struct inode *inode, wake_up(>wait); } +void btrfs_clean_ordered_extent(struct inode *inode, u64 file_offset, + u64 ram_len) +{ + struct btrfs_ordered_extent *entry; + struct btrfs_root *root = BTRFS_I(inode)->root; + + entry =