[BUG]
Btrfs will fail generic/750 randomly if its sector size is smaller than
page size.
One of the warning looks like this:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 90263 at fs/btrfs/ordered-data.c:360 can_finish_ordered_extent+0x33c/0x390 [btrfs]
CPU: 1 UID: 0 PID: 90263 Comm: kworker/u18:1 Tainted: G OE 6.12.0-rc3-custom+ #79
Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
pc : can_finish_ordered_extent+0x33c/0x390 [btrfs]
lr : can_finish_ordered_extent+0xdc/0x390 [btrfs]
Call trace:
can_finish_ordered_extent+0x33c/0x390 [btrfs]
btrfs_mark_ordered_io_finished+0x130/0x2b8 [btrfs]
extent_writepage+0xfc/0x338 [btrfs]
extent_write_cache_pages+0x1d4/0x4b8 [btrfs]
btrfs_writepages+0x94/0x158 [btrfs]
do_writepages+0x74/0x190
filemap_fdatawrite_wbc+0x88/0xc8
start_delalloc_inodes+0x180/0x3b0 [btrfs]
btrfs_start_delalloc_roots+0x17c/0x288 [btrfs]
shrink_delalloc+0x11c/0x280 [btrfs]
flush_space+0x27c/0x310 [btrfs]
btrfs_async_reclaim_metadata_space+0xcc/0x208 [btrfs]
process_one_work+0x228/0x670
worker_thread+0x1bc/0x360
kthread+0x100/0x118
ret_from_fork+0x10/0x20
irq event stamp: 9784200
hardirqs last enabled at (9784199): [<ffffd21ec54dc01c>] _raw_spin_unlock_irqrestore+0x74/0x80
hardirqs last disabled at (9784200): [<ffffd21ec54db374>] _raw_spin_lock_irqsave+0x8c/0xa0
softirqs last enabled at (9784148): [<ffffd21ec472ff44>] handle_softirqs+0x45c/0x4b0
softirqs last disabled at (9784141): [<ffffd21ec46d01e4>] __do_softirq+0x1c/0x28
---[ end trace 0000000000000000 ]---
BTRFS critical (device dm-2): bad ordered extent accounting, root=5 ino=1492 OE offset=1654784 OE len=57344 to_dec=49152 left=0
[CAUSE]
There are several error paths not properly handling during folio
writeback:
1) Partially submitted folio
During extent_writepage_io() if some error happened (the only
possible case is submit_one_sector() failed to grab an extent map),
then we can have partially submitted folio.
Since extent_writepage_io() failed, we need to call
btrfs_mark_ordered_io_finished() to cleanup the submitted range.
But we will call btrfs_mark_ordered_io_finished() for submitted range
too, causing double accounting.
2) Partially created ordered extents
We cal also fail at writepage_delalloc(), which will stop creating
new ordered extents if it hit any error from
btrfs_run_delalloc_range().
In that case, we will call btrfs_mark_ordered_io_finished() for
ranges where there is no ordered extent at all.
Both bugs are only affecting sector size < page size cases.
[FIX]
- Introduce a new member btrfs_bio_ctrl::last_submitted
This will trace the last sector submitted through
extent_writepage_io().
So for the above extent_writepage() case, we will know exactly which
sectors are submitted and should not do the ordered extent accounting.
- Clear the submit_bitmap for ranges where no ordered extent is created
So if btrfs_run_delalloc_range() failed for a range, it will be not
cleaned up.
- Introduce a helper cleanup_ordered_extents()
This will do a sector-by-sector cleanup with
btrfs_bio_ctrl::last_submitted and btrfs_bio_ctrl::submit_bitmap into
consideartion.
Using @last_submitted is to avoid double accounting on the submitted
ranges.
Meanwhile using @submit_bitmap is to avoid touching ranges going
through compression.
cc: stable@xxxxxxxxxxxxxxx # 5.15+
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/extent_io.c | 54 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 47 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index e629d2ee152a..1c2246d36672 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -108,6 +108,14 @@ struct btrfs_bio_ctrl {
* This is to avoid touching ranges covered by compression/inline.
*/
unsigned long submit_bitmap;
+
+ /*
+ * The end (exclusive) of the last submitted range in the folio.
+ *
+ * This is for sector size < page size case where we may hit error
+ * half way.
+ */
+ u64 last_submitted;
};
static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
@@ -1254,11 +1262,18 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
/*
* We have some ranges that's going to be submitted asynchronously
- * (compression or inline). These range have their own control
+ * (compression or inline, ret > 0). These range have their own control
* on when to unlock the pages. We should not touch them
- * anymore, so clear the range from the submission bitmap.
+ * anymore.
+ *
+ * We can also have some ranges where we didn't even call
+ * btrfs_run_delalloc_range() (as previous run failed, ret < 0).
+ * These error ranges should not be submitted nor cleaned up as
+ * there is no ordered extent allocated for them.
+ *
+ * For either cases, we should clear the submit_bitmap.
*/
- if (ret > 0) {
+ if (ret) {
unsigned int start_bit = (found_start - page_start) >>
fs_info->sectorsize_bits;
unsigned int end_bit = (min(page_end + 1, found_start + found_len) -
@@ -1435,6 +1450,7 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode,
ret = submit_one_sector(inode, folio, cur, bio_ctrl, i_size);
if (ret < 0)
goto out;
+ bio_ctrl->last_submitted = cur + fs_info->sectorsize;
submitted_io = true;
}
out:
@@ -1453,6 +1469,24 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode,
return ret;
}
+static void cleanup_ordered_extents(struct btrfs_inode *inode,
+ struct folio *folio, u64 file_pos,
+ u64 num_bytes, unsigned long *bitmap)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ unsigned int cur_bit = (file_pos - folio_pos(folio)) >> fs_info->sectorsize_bits;
+
+ for_each_set_bit_from(cur_bit, bitmap, fs_info->sectors_per_page) {
+ u64 cur_pos = folio_pos(folio) + (cur_bit << fs_info->sectorsize_bits);
+
+ if (cur_pos >= file_pos + num_bytes)
+ break;
+
+ btrfs_mark_ordered_io_finished(inode, folio, cur_pos,
+ fs_info->sectorsize, false);
+ }
+}
+
/*
* the writepage semantics are similar to regular writepage. extent
* records are inserted to lock ranges in the tree, and as dirty areas
@@ -1492,6 +1526,7 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl
* The proper bitmap can only be initialized until writepage_delalloc().
*/
bio_ctrl->submit_bitmap = (unsigned long)-1;
+ bio_ctrl->last_submitted = page_start;
ret = set_folio_extent_mapped(folio);
if (ret < 0)
goto done;
@@ -1511,8 +1546,10 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl
done:
if (ret) {
- btrfs_mark_ordered_io_finished(BTRFS_I(inode), folio,
- page_start, PAGE_SIZE, !ret);
+ cleanup_ordered_extents(BTRFS_I(inode), folio,
+ bio_ctrl->last_submitted,
+ page_start + PAGE_SIZE - bio_ctrl->last_submitted,
+ &bio_ctrl->submit_bitmap);
mapping_set_error(folio->mapping, ret);
}
@@ -2288,14 +2325,17 @@ void extent_write_locked_range(struct inode *inode, const struct folio *locked_f
* extent_writepage_io() will do the truncation correctly.
*/
bio_ctrl.submit_bitmap = (unsigned long)-1;
+ bio_ctrl.last_submitted = cur;
ret = extent_writepage_io(BTRFS_I(inode), folio, cur, cur_len,
&bio_ctrl, i_size);
if (ret == 1)
goto next_page;
if (ret) {
- btrfs_mark_ordered_io_finished(BTRFS_I(inode), folio,
- cur, cur_len, !ret);
+ cleanup_ordered_extents(BTRFS_I(inode), folio,
+ bio_ctrl.last_submitted,
+ cur_end + 1 - bio_ctrl.last_submitted,
+ &bio_ctrl.submit_bitmap);
mapping_set_error(mapping, ret);
}
btrfs_folio_end_lock(fs_info, folio, cur, cur_len);
--
2.47.0
