This provides basic DIO support for reads only. It does not do any of the work
to recover from mismatching checksums, that will come later. A few design
changes have been made from Jim's code (sorry Jim!)
1) Use the generic direct-io code. Jim originally re-wrote all the generic DIO
code in order to account for all of BTRFS's oddities, but thanks to that work it
seems like the best bet is to just ignore compression and such and just opt to
fallback on buffered IO.
2) Fallback on buffered IO for compressed or inline extents. Jim's code did
it's own buffering to make dio with compressed extents work. Now we just
fallback onto normal buffered IO.
3) Lock the entire range during DIO. I originally had it so we would lock the
extents as get_block was called, and then unlock them as the endio function was
called, which worked great, but if we ever had an error in the submit_io hook,
we could have locked an extent that would never be submitted for IO, so we
wouldn't be able to unlock it, so this solution fixed that problem and made it a
bit cleaner.
I've tested this with fsx and everything works great. This patch depends on my
dio and filemap.c patches to work. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
---
fs/btrfs/ctree.h | 2 +
fs/btrfs/file-item.c | 25 +++++-
fs/btrfs/inode.c | 208 +++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 230 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 746a724..36994e8 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2257,6 +2257,8 @@ int btrfs_del_csums(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 bytenr, u64 len);
int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
struct bio *bio, u32 *dst);
+int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
+ struct bio *bio, u64 logical_offset, u32 *dst);
int btrfs_insert_file_extent(struct btrfs_trans_handle ...
