| Message ID | 20170308022552.14686-2-quwenruo@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 8, 2017 at 2:25 AM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote: > [BUG] > If run_delalloc_range() returns error and there is already some ordered > extents created, btrfs will be hanged 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 > > [CAUSE] > > |<------------------ delalloc range --------------------------->| > | OE 1 | OE 2 | ... | OE n | > |<>| |<---------- cleanup range --------->| > || > \_=> First page handled by end_extent_writepage() in __extent_writepage() > > The problem is caused by error handler of run_delalloc_range(), which > doesn't handle any created ordered extents, leaving them waiting on > btrfs_finish_ordered_io() to finish. > > However after run_delalloc_range() returns error, __extent_writepage() > won't submit bio, so btrfs_writepage_end_io_hook() won't be triggered > except the first page, and btrfs_finish_ordered_io() won't be triggered > for created ordered extents either. > > So OE 2~n will hang forever, and if OE 1 is larger than one page, it > will also hang. > > [FIX] > Introduce btrfs_cleanup_ordered_extents() function to cleanup created > ordered extents and finish them manually. > > The function is based on existing > btrfs_endio_direct_write_update_ordered() function, and modify it to > act just like btrfs_writepage_endio_hook() but handles specified range > other than one page. > > After fix, delalloc error will be handled like: > > |<------------------ delalloc range --------------------------->| > | OE 1 | OE 2 | ... | OE n | > |<>|<-------- ----------->|<------ old error handler --------->| > || || > || \_=> Cleaned up by cleanup_ordered_extents() > \_=> First page handled by end_extent_writepage() in __extent_writepage() > > Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> thanks > Signed-off-by: Filipe Manana <fdmanana@suse.com> > --- > v2: > Add BTRFS_ORDERED_SKIP_METADATA flag to avoid double reducing > outstanding extents, which is already done by > extent_clear_unlock_delalloc() with EXTENT_DO_ACCOUNT control bit > v3: > Skip first page to avoid underflow ordered->bytes_left. > Fix range passed in cow_file_range() which doesn't cover the whole > extent. > Expend extent_clear_unlock_delalloc() range to allow them to handle > metadata release. > v4: > Don't use extra bit to skip metadata freeing for ordered extent, > but only handle btrfs_reloc_clone_csums() error just before processing > next extent. > This makes error handle much easier for run_delalloc_nocow(). > v5: > Variant gramma and comment fixes suggested by Filipe Manana > Enhanced commit message to focus on the generic error handler bug, > pointed out by Filipe Manana > Adding missing wq/func user in __endio_write_update_ordered(), pointed > out by Filipe Manana. > Enhanced commit message with ascii art to explain the bug more easily. > Fix a bug which can leads to corrupted extent allocation, exposed by > Filipe Manana. > v6: > Split the metadata underflow fix to another patch. > Use better comment and btrfs_cleanup_ordered_extent() implementation > from Filipe Manana. > v7: > Add back const prefix > --- > fs/btrfs/inode.c | 63 ++++++++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 48 insertions(+), 15 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index fe588bf30d02..d3bc68bbe0e7 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -115,6 +115,31 @@ static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len, > u64 ram_bytes, int compress_type, > int type); > > +static void __endio_write_update_ordered(struct inode *inode, > + const u64 offset, const u64 bytes, > + const bool uptodate); > + > +/* > + * Cleanup all submitted ordered extents in specified range to handle errors > + * from the fill_dellaloc() callback. > + * > + * NOTE: caller must ensure that when an error happens, it can not call > + * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING > + * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata > + * to be released, which we want to happen only when finishing the ordered > + * extent (btrfs_finish_ordered_io()). Also note that the caller of the > + * fill_delalloc() callback already does proper cleanup for the first page of > + * the range, that is, it invokes the callback writepage_end_io_hook() for the > + * range of the first page. > + */ > +static inline void btrfs_cleanup_ordered_extents(struct inode *inode, > + const u64 offset, > + const u64 bytes) > +{ > + return __endio_write_update_ordered(inode, offset + PAGE_SIZE, > + bytes - PAGE_SIZE, false); > +} > + > static int btrfs_dirty_inode(struct inode *inode); > > #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS > @@ -1536,6 +1561,8 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page, > ret = cow_file_range_async(inode, locked_page, start, end, > page_started, nr_written); > } > + if (ret) > + btrfs_cleanup_ordered_extents(inode, start, end - start + 1); > return ret; > } > > @@ -8142,17 +8169,26 @@ static void btrfs_endio_direct_read(struct bio *bio) > bio_put(bio); > } > > -static void btrfs_endio_direct_write_update_ordered(struct inode *inode, > - const u64 offset, > - const u64 bytes, > - const int uptodate) > +static void __endio_write_update_ordered(struct inode *inode, > + const u64 offset, const u64 bytes, > + const bool uptodate) > { > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > struct btrfs_ordered_extent *ordered = NULL; > + struct btrfs_workqueue *wq; > + btrfs_work_func_t func; > u64 ordered_offset = offset; > u64 ordered_bytes = bytes; > int ret; > > + if (btrfs_is_free_space_inode(BTRFS_I(inode))) { > + wq = fs_info->endio_freespace_worker; > + func = btrfs_freespace_write_helper; > + } else { > + wq = fs_info->endio_write_workers; > + func = btrfs_endio_write_helper; > + } > + > again: > ret = btrfs_dec_test_first_ordered_pending(inode, &ordered, > &ordered_offset, > @@ -8161,9 +8197,8 @@ static void btrfs_endio_direct_write_update_ordered(struct inode *inode, > if (!ret) > goto out_test; > > - btrfs_init_work(&ordered->work, btrfs_endio_write_helper, > - finish_ordered_fn, NULL, NULL); > - btrfs_queue_work(fs_info->endio_write_workers, &ordered->work); > + btrfs_init_work(&ordered->work, func, finish_ordered_fn, NULL, NULL); > + btrfs_queue_work(wq, &ordered->work); > out_test: > /* > * our bio might span multiple ordered extents. If we haven't > @@ -8181,10 +8216,8 @@ static void btrfs_endio_direct_write(struct bio *bio) > struct btrfs_dio_private *dip = bio->bi_private; > struct bio *dio_bio = dip->dio_bio; > > - btrfs_endio_direct_write_update_ordered(dip->inode, > - dip->logical_offset, > - dip->bytes, > - !bio->bi_error); > + __endio_write_update_ordered(dip->inode, dip->logical_offset, > + dip->bytes, !bio->bi_error); > > kfree(dip); > > @@ -8545,10 +8578,10 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode, > io_bio = NULL; > } else { > if (write) > - btrfs_endio_direct_write_update_ordered(inode, > + __endio_write_update_ordered(inode, > file_offset, > dio_bio->bi_iter.bi_size, > - 0); > + false); > else > unlock_extent(&BTRFS_I(inode)->io_tree, file_offset, > file_offset + dio_bio->bi_iter.bi_size - 1); > @@ -8683,11 +8716,11 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > */ > if (dio_data.unsubmitted_oe_range_start < > dio_data.unsubmitted_oe_range_end) > - btrfs_endio_direct_write_update_ordered(inode, > + __endio_write_update_ordered(inode, > dio_data.unsubmitted_oe_range_start, > dio_data.unsubmitted_oe_range_end - > dio_data.unsubmitted_oe_range_start, > - 0); > + false); > } else if (ret >= 0 && (size_t)ret < count) > btrfs_delalloc_release_space(inode, offset, > count - (size_t)ret); > -- > 2.12.0 > > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Mar 08, 2017 at 10:25:52AM +0800, Qu Wenruo wrote: > [BUG] > If run_delalloc_range() returns error and there is already some ordered > extents created, btrfs will be hanged 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 > > [CAUSE] > > |<------------------ delalloc range --------------------------->| > | OE 1 | OE 2 | ... | OE n | > |<>| |<---------- cleanup range --------->| > || > \_=> First page handled by end_extent_writepage() in __extent_writepage() > > The problem is caused by error handler of run_delalloc_range(), which > doesn't handle any created ordered extents, leaving them waiting on > btrfs_finish_ordered_io() to finish. > > However after run_delalloc_range() returns error, __extent_writepage() > won't submit bio, so btrfs_writepage_end_io_hook() won't be triggered > except the first page, and btrfs_finish_ordered_io() won't be triggered > for created ordered extents either. > > So OE 2~n will hang forever, and if OE 1 is larger than one page, it > will also hang. > > [FIX] > Introduce btrfs_cleanup_ordered_extents() function to cleanup created > ordered extents and finish them manually. > > The function is based on existing > btrfs_endio_direct_write_update_ordered() function, and modify it to > act just like btrfs_writepage_endio_hook() but handles specified range > other than one page. > > After fix, delalloc error will be handled like: > > |<------------------ delalloc range --------------------------->| > | OE 1 | OE 2 | ... | OE n | > |<>|<-------- ----------->|<------ old error handler --------->| > || || > || \_=> Cleaned up by cleanup_ordered_extents() > \_=> First page handled by end_extent_writepage() in __extent_writepage() Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Thanks, -liubo > > Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> > Signed-off-by: Filipe Manana <fdmanana@suse.com> > --- > v2: > Add BTRFS_ORDERED_SKIP_METADATA flag to avoid double reducing > outstanding extents, which is already done by > extent_clear_unlock_delalloc() with EXTENT_DO_ACCOUNT control bit > v3: > Skip first page to avoid underflow ordered->bytes_left. > Fix range passed in cow_file_range() which doesn't cover the whole > extent. > Expend extent_clear_unlock_delalloc() range to allow them to handle > metadata release. > v4: > Don't use extra bit to skip metadata freeing for ordered extent, > but only handle btrfs_reloc_clone_csums() error just before processing > next extent. > This makes error handle much easier for run_delalloc_nocow(). > v5: > Variant gramma and comment fixes suggested by Filipe Manana > Enhanced commit message to focus on the generic error handler bug, > pointed out by Filipe Manana > Adding missing wq/func user in __endio_write_update_ordered(), pointed > out by Filipe Manana. > Enhanced commit message with ascii art to explain the bug more easily. > Fix a bug which can leads to corrupted extent allocation, exposed by > Filipe Manana. > v6: > Split the metadata underflow fix to another patch. > Use better comment and btrfs_cleanup_ordered_extent() implementation > from Filipe Manana. > v7: > Add back const prefix > --- > fs/btrfs/inode.c | 63 ++++++++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 48 insertions(+), 15 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index fe588bf30d02..d3bc68bbe0e7 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -115,6 +115,31 @@ static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len, > u64 ram_bytes, int compress_type, > int type); > > +static void __endio_write_update_ordered(struct inode *inode, > + const u64 offset, const u64 bytes, > + const bool uptodate); > + > +/* > + * Cleanup all submitted ordered extents in specified range to handle errors > + * from the fill_dellaloc() callback. > + * > + * NOTE: caller must ensure that when an error happens, it can not call > + * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING > + * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata > + * to be released, which we want to happen only when finishing the ordered > + * extent (btrfs_finish_ordered_io()). Also note that the caller of the > + * fill_delalloc() callback already does proper cleanup for the first page of > + * the range, that is, it invokes the callback writepage_end_io_hook() for the > + * range of the first page. > + */ > +static inline void btrfs_cleanup_ordered_extents(struct inode *inode, > + const u64 offset, > + const u64 bytes) > +{ > + return __endio_write_update_ordered(inode, offset + PAGE_SIZE, > + bytes - PAGE_SIZE, false); > +} > + > static int btrfs_dirty_inode(struct inode *inode); > > #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS > @@ -1536,6 +1561,8 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page, > ret = cow_file_range_async(inode, locked_page, start, end, > page_started, nr_written); > } > + if (ret) > + btrfs_cleanup_ordered_extents(inode, start, end - start + 1); > return ret; > } > > @@ -8142,17 +8169,26 @@ static void btrfs_endio_direct_read(struct bio *bio) > bio_put(bio); > } > > -static void btrfs_endio_direct_write_update_ordered(struct inode *inode, > - const u64 offset, > - const u64 bytes, > - const int uptodate) > +static void __endio_write_update_ordered(struct inode *inode, > + const u64 offset, const u64 bytes, > + const bool uptodate) > { > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > struct btrfs_ordered_extent *ordered = NULL; > + struct btrfs_workqueue *wq; > + btrfs_work_func_t func; > u64 ordered_offset = offset; > u64 ordered_bytes = bytes; > int ret; > > + if (btrfs_is_free_space_inode(BTRFS_I(inode))) { > + wq = fs_info->endio_freespace_worker; > + func = btrfs_freespace_write_helper; > + } else { > + wq = fs_info->endio_write_workers; > + func = btrfs_endio_write_helper; > + } > + > again: > ret = btrfs_dec_test_first_ordered_pending(inode, &ordered, > &ordered_offset, > @@ -8161,9 +8197,8 @@ static void btrfs_endio_direct_write_update_ordered(struct inode *inode, > if (!ret) > goto out_test; > > - btrfs_init_work(&ordered->work, btrfs_endio_write_helper, > - finish_ordered_fn, NULL, NULL); > - btrfs_queue_work(fs_info->endio_write_workers, &ordered->work); > + btrfs_init_work(&ordered->work, func, finish_ordered_fn, NULL, NULL); > + btrfs_queue_work(wq, &ordered->work); > out_test: > /* > * our bio might span multiple ordered extents. If we haven't > @@ -8181,10 +8216,8 @@ static void btrfs_endio_direct_write(struct bio *bio) > struct btrfs_dio_private *dip = bio->bi_private; > struct bio *dio_bio = dip->dio_bio; > > - btrfs_endio_direct_write_update_ordered(dip->inode, > - dip->logical_offset, > - dip->bytes, > - !bio->bi_error); > + __endio_write_update_ordered(dip->inode, dip->logical_offset, > + dip->bytes, !bio->bi_error); > > kfree(dip); > > @@ -8545,10 +8578,10 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode, > io_bio = NULL; > } else { > if (write) > - btrfs_endio_direct_write_update_ordered(inode, > + __endio_write_update_ordered(inode, > file_offset, > dio_bio->bi_iter.bi_size, > - 0); > + false); > else > unlock_extent(&BTRFS_I(inode)->io_tree, file_offset, > file_offset + dio_bio->bi_iter.bi_size - 1); > @@ -8683,11 +8716,11 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > */ > if (dio_data.unsubmitted_oe_range_start < > dio_data.unsubmitted_oe_range_end) > - btrfs_endio_direct_write_update_ordered(inode, > + __endio_write_update_ordered(inode, > dio_data.unsubmitted_oe_range_start, > dio_data.unsubmitted_oe_range_end - > dio_data.unsubmitted_oe_range_start, > - 0); > + false); > } else if (ret >= 0 && (size_t)ret < count) > btrfs_delalloc_release_space(inode, offset, > count - (size_t)ret); > -- > 2.12.0 > > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index fe588bf30d02..d3bc68bbe0e7 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -115,6 +115,31 @@ static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len, u64 ram_bytes, int compress_type, int type); +static void __endio_write_update_ordered(struct inode *inode, + const u64 offset, const u64 bytes, + const bool uptodate); + +/* + * Cleanup all submitted ordered extents in specified range to handle errors + * from the fill_dellaloc() callback. + * + * NOTE: caller must ensure that when an error happens, it can not call + * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING + * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata + * to be released, which we want to happen only when finishing the ordered + * extent (btrfs_finish_ordered_io()). Also note that the caller of the + * fill_delalloc() callback already does proper cleanup for the first page of + * the range, that is, it invokes the callback writepage_end_io_hook() for the + * range of the first page. + */ +static inline void btrfs_cleanup_ordered_extents(struct inode *inode, + const u64 offset, + const u64 bytes) +{ + return __endio_write_update_ordered(inode, offset + PAGE_SIZE, + bytes - PAGE_SIZE, false); +} + static int btrfs_dirty_inode(struct inode *inode); #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS @@ -1536,6 +1561,8 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page, ret = cow_file_range_async(inode, locked_page, start, end, page_started, nr_written); } + if (ret) + btrfs_cleanup_ordered_extents(inode, start, end - start + 1); return ret; } @@ -8142,17 +8169,26 @@ static void btrfs_endio_direct_read(struct bio *bio) bio_put(bio); } -static void btrfs_endio_direct_write_update_ordered(struct inode *inode, - const u64 offset, - const u64 bytes, - const int uptodate) +static void __endio_write_update_ordered(struct inode *inode, + const u64 offset, const u64 bytes, + const bool uptodate) { struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); struct btrfs_ordered_extent *ordered = NULL; + struct btrfs_workqueue *wq; + btrfs_work_func_t func; u64 ordered_offset = offset; u64 ordered_bytes = bytes; int ret; + if (btrfs_is_free_space_inode(BTRFS_I(inode))) { + wq = fs_info->endio_freespace_worker; + func = btrfs_freespace_write_helper; + } else { + wq = fs_info->endio_write_workers; + func = btrfs_endio_write_helper; + } + again: ret = btrfs_dec_test_first_ordered_pending(inode, &ordered, &ordered_offset, @@ -8161,9 +8197,8 @@ static void btrfs_endio_direct_write_update_ordered(struct inode *inode, if (!ret) goto out_test; - btrfs_init_work(&ordered->work, btrfs_endio_write_helper, - finish_ordered_fn, NULL, NULL); - btrfs_queue_work(fs_info->endio_write_workers, &ordered->work); + btrfs_init_work(&ordered->work, func, finish_ordered_fn, NULL, NULL); + btrfs_queue_work(wq, &ordered->work); out_test: /* * our bio might span multiple ordered extents. If we haven't @@ -8181,10 +8216,8 @@ static void btrfs_endio_direct_write(struct bio *bio) struct btrfs_dio_private *dip = bio->bi_private; struct bio *dio_bio = dip->dio_bio; - btrfs_endio_direct_write_update_ordered(dip->inode, - dip->logical_offset, - dip->bytes, - !bio->bi_error); + __endio_write_update_ordered(dip->inode, dip->logical_offset, + dip->bytes, !bio->bi_error); kfree(dip); @@ -8545,10 +8578,10 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode, io_bio = NULL; } else { if (write) - btrfs_endio_direct_write_update_ordered(inode, + __endio_write_update_ordered(inode, file_offset, dio_bio->bi_iter.bi_size, - 0); + false); else unlock_extent(&BTRFS_I(inode)->io_tree, file_offset, file_offset + dio_bio->bi_iter.bi_size - 1); @@ -8683,11 +8716,11 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) */ if (dio_data.unsubmitted_oe_range_start < dio_data.unsubmitted_oe_range_end) - btrfs_endio_direct_write_update_ordered(inode, + __endio_write_update_ordered(inode, dio_data.unsubmitted_oe_range_start, dio_data.unsubmitted_oe_range_end - dio_data.unsubmitted_oe_range_start, - 0); + false); } else if (ret >= 0 && (size_t)ret < count) btrfs_delalloc_release_space(inode, offset, count - (size_t)ret);