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Subject[PATCH 4.19 17/71] btrfs: extent_io: Handle errors better in extent_write_full_page()
Date
From: Qu Wenruo <wqu@suse.com>

commit 3065976b045f77a910809fa7699f99a1e7c0dbbb upstream.

Since now flush_write_bio() could return error, kill the BUG_ON() first.
Then don't call flush_write_bio() unconditionally, instead we check the
return value from __extent_writepage() first.

If __extent_writepage() fails, we do cleanup, and return error without
submitting the possible corrupted or half-baked bio.

If __extent_writepage() successes, then we call flush_write_bio() and
return the result.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/extent_io.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -160,6 +160,16 @@ static int __must_check submit_one_bio(s
return blk_status_to_errno(ret);
}

+/* Cleanup unsubmitted bios */
+static void end_write_bio(struct extent_page_data *epd, int ret)
+{
+ if (epd->bio) {
+ epd->bio->bi_status = errno_to_blk_status(ret);
+ bio_endio(epd->bio);
+ epd->bio = NULL;
+ }
+}
+
/*
* Submit bio from extent page data via submit_one_bio
*
@@ -3461,6 +3471,9 @@ done:
* records are inserted to lock ranges in the tree, and as dirty areas
* are found, they are marked writeback. Then the lock bits are removed
* and the end_io handler clears the writeback ranges
+ *
+ * Return 0 if everything goes well.
+ * Return <0 for error.
*/
static int __extent_writepage(struct page *page, struct writeback_control *wbc,
struct extent_page_data *epd)
@@ -3528,6 +3541,7 @@ done:
end_extent_writepage(page, ret, start, page_end);
}
unlock_page(page);
+ ASSERT(ret <= 0);
return ret;

done_unlocked:
@@ -4067,7 +4081,6 @@ retry:
int extent_write_full_page(struct page *page, struct writeback_control *wbc)
{
int ret;
- int flush_ret;
struct extent_page_data epd = {
.bio = NULL,
.tree = &BTRFS_I(page->mapping->host)->io_tree,
@@ -4076,9 +4089,14 @@ int extent_write_full_page(struct page *
};

ret = __extent_writepage(page, wbc, &epd);
+ ASSERT(ret <= 0);
+ if (ret < 0) {
+ end_write_bio(&epd, ret);
+ return ret;
+ }

- flush_ret = flush_write_bio(&epd);
- BUG_ON(flush_ret < 0);
+ ret = flush_write_bio(&epd);
+ ASSERT(ret <= 0);
return ret;
}


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