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authorQu Wenruo <quwenruo@cn.fujitsu.com>2017-03-08 10:25:52 +0800
committerFilipe Manana <fdmanana@suse.com>2017-04-26 16:27:21 +0100
commit524272607e882d04e6d1a70d41fcbed819445ab9 (patch)
tree3ade1425fa0a2d387aa939ec8d11478bd1f764e8
parent4dbd80fb9176f23c78cecd0a8285001cd2066425 (diff)
btrfs: Handle delalloc error correctly to avoid ordered extent hang
[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> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Filipe Manana <fdmanana@suse.com>
-rw-r--r--fs/btrfs/inode.c63
1 files changed, 48 insertions, 15 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 844bb896f5ac..b8b2a3cbdbe1 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;
}
@@ -8154,17 +8181,26 @@ 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,
@@ -8173,9 +8209,8 @@ again:
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
@@ -8193,10 +8228,8 @@ 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);
@@ -8557,10 +8590,10 @@ free_ordered:
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);
@@ -8695,11 +8728,11 @@ 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);