Commit f9f15de8 authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: do not double complete bio on errors during compressed reads 



I hit some weird panics while fixing up the error handling from
btrfs_lookup_bio_sums().  Turns out the compression path will complete
the bio we use if we set up any of the compression bios and then return
an error, and then btrfs_submit_data_bio() will also call bio_endio() on
the bio.

Fix this by making btrfs_submit_compressed_read() responsible for
calling bio_endio() on the bio if there are any errors.  Currently it
was only doing it if we created the compression bios, otherwise it was
depending on btrfs_submit_data_bio() to do the right thing.  This
creates the above problem, so fix up btrfs_submit_compressed_read() to
always call bio_endio() in case of an error, and then simply return from
btrfs_submit_data_bio() if we had to call
btrfs_submit_compressed_read().

Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 606f82e7

fs/btrfs/compression.c

+14 −6
Original line number Diff line number Diff line
@@ -811,7 +811,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 
	u64 em_len;

	u64 em_start;

	struct extent_map *em;

	blk_status_t ret = BLK_STS_RESOURCE;

	blk_status_t ret;

	int faili = 0;

	u8 *sums;
@@ -824,14 +824,18 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 
	read_lock(&em_tree->lock);

	em = lookup_extent_mapping(em_tree, file_offset, fs_info->sectorsize);

	read_unlock(&em_tree->lock);

	if (!em)

		return BLK_STS_IOERR;

	if (!em) {

		ret = BLK_STS_IOERR;

		goto out;

	}



	ASSERT(em->compress_type != BTRFS_COMPRESS_NONE);

	compressed_len = em->block_len;

	cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);

	if (!cb)

	if (!cb) {

		ret = BLK_STS_RESOURCE;

		goto out;

	}



	refcount_set(&cb->pending_sectors, compressed_len >> fs_info->sectorsize_bits);

	cb->status = BLK_STS_OK;
@@ -854,8 +858,10 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 
	nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);

	cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),

				       GFP_NOFS);

	if (!cb->compressed_pages)

	if (!cb->compressed_pages) {

		ret = BLK_STS_RESOURCE;

		goto fail1;

	}



	for (pg_index = 0; pg_index < nr_pages; pg_index++) {

		cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS);
@@ -941,7 +947,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 
			comp_bio = NULL;

		}

	}

	return 0;

	return BLK_STS_OK;



fail2:

	while (faili >= 0) {
@@ -954,6 +960,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 
	kfree(cb);

out:

	free_extent_map(em);

	bio->bi_status = ret;

	bio_endio(bio);

	return ret;

finish_cb:

	if (comp_bio) {

fs/btrfs/inode.c

+7 −1
Original line number Diff line number Diff line
@@ -2543,10 +2543,15 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio, 
			goto out;



		if (bio_flags & EXTENT_BIO_COMPRESSED) {

			/*

			 * btrfs_submit_compressed_read will handle completing

			 * the bio if there were any errors, so just return

			 * here.

			 */

			ret = btrfs_submit_compressed_read(inode, bio,

							   mirror_num,

							   bio_flags);

			goto out;

			goto out_no_endio;

		} else {

			/*

			 * Lookup bio sums does extra checks around whether we
@@ -2580,6 +2585,7 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio, 
		bio->bi_status = ret;

		bio_endio(bio);

	}

out_no_endio:

	return ret;

}