We have a few places where we skip doing csums if we mounted with one of
the rescue options that ignores bad csum roots.  In the future when
there are multiple csum roots it'll be costly to check and see if there
are any missing csum roots, so simply add a flag to indicate the fs
should skip loading csums in case of errors.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/compression.c | 3 ++-
 fs/btrfs/ctree.h       | 2 ++
 fs/btrfs/disk-io.c     | 5 +++++
 fs/btrfs/file-item.c   | 3 ++-
 fs/btrfs/inode.c       | 4 ++--
 5 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 1d071c8d6fff..a76107d6f7f2 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c

@@ -156,7 +156,8 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
 	struct compressed_bio *cb = bio->bi_private;
 	u8 *cb_sum = cb->sums;
 
-	if (!fs_info->csum_root || (inode->flags & BTRFS_INODE_NODATASUM))
+	if ((inode->flags & BTRFS_INODE_NODATASUM) ||
+	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
 		return 0;
 
 	shash->tfm = fs_info->csum_shash;

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index dac5741cb6fa..13bd6fc3901a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h

@@ -143,6 +143,8 @@ enum {
 	BTRFS_FS_STATE_DEV_REPLACING,
 	/* The btrfs_fs_info created for self-tests */
 	BTRFS_FS_STATE_DUMMY_FS_INFO,
+
+	BTRFS_FS_STATE_NO_CSUMS,
 };
 
 #define BTRFS_BACKREF_REV_MAX		256

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1ada4c96ef71..898b4ff83718 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c

@@ -2475,11 +2475,16 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
 			if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
 				ret = PTR_ERR(root);
 				goto out;
+			} else {
+				set_bit(BTRFS_FS_STATE_NO_CSUMS,
+					&fs_info->fs_state);
 			}
 		} else {
 			set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
 			fs_info->csum_root = root;
 		}
+	} else {
+		set_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state);
 	}
 
 	/*

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 359f3a047360..4904286139bf 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c

@@ -376,7 +376,8 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
 	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
 	int count = 0;
 
-	if (!fs_info->csum_root || (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM))
+	if ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
+	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
 		return BLK_STS_OK;
 
 	/*

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 9e81fd94ab09..6d14dd2cf36e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c

@@ -2516,7 +2516,7 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
 	int async = !atomic_read(&BTRFS_I(inode)->sync_writers);
 
 	skip_sum = (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
-		   !fs_info->csum_root;
+		test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state);
 
 	if (btrfs_is_free_space_inode(BTRFS_I(inode)))
 		metadata = BTRFS_WQ_ENDIO_FREE_SPACE;

@@ -3314,7 +3314,7 @@ unsigned int btrfs_verify_data_csum(struct btrfs_bio *bbio,
 	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
 		return 0;
 
-	if (!root->fs_info->csum_root)
+	if (unlikely(test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state)))
 		return 0;