Btrfs: add basic DIO read support V2
Subsystems (3)
PATCH 5/5 Btrfs: add basic DIO read support V2
V1->V2
-Use __blockdev_direct_IO instead of helper
-Use KM_IRQ0 for kmap instead of KM_USER0
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,
--- fs/btrfs/ctree.h | 2 + fs/btrfs/file-item.c | 25 +++++- fs/btrfs/inode.c | 205 +++++++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 227 insertions(+), 5 deletions(-)
fs/btrfs/ctree.h +2 -0
@@ -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 *trans, struct btrfs_root *root, u64 objectid, u64 pos,
fs/btrfs/file-item.c +21 -4
@@ -149,13 +149,14 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans, } -int btrfs_lookup_bio_sums (struct btrfs_root *root,struct inode *inode, -struct bio *bio,u32 *dst) +static int __btrfs_lookup_bio_sums (struct btrfs_root *root, +struct inode *inode,struct bio *bio, +u64 logical_offset,u32 *dst,int dio) {u32 sum;struct bio_vec *bvec = bio->bi_io_vec;int bio_index =0 ; -u64 offset; +u64 offset =0 ;u64 item_start_offset =0 ;u64 item_last_offset =0 ;u64 disk_bytenr;
@@ -174,8 +175,11 @@ int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,WARN_ON (bio->bi_vcnt <=0 ); disk_bytenr = (u64 )bio->bi_sector <<9 ; +if (dio) + offset = logical_offset;while (bio_index < bio->bi_vcnt) { - offset =page_offset (bvec->bv_page) + bvec->bv_offset; +if (!dio) + offset =page_offset (bvec->bv_page) + bvec->bv_offset; ret =btrfs_find_ordered_sum (inode, offset, disk_bytenr, &sum);if (ret ==0 ) goto found;
@@ -238,6 +242,7 @@ found:else set_state_private (io_tree, offset, sum); disk_bytenr += bvec->bv_len; + offset += bvec->bv_len; bio_index++; bvec++; }
@@ -245,6 +250,18 @@ found:return 0 ; } +int btrfs_lookup_bio_sums (struct btrfs_root *root,struct inode *inode, +struct bio *bio,u32 *dst) +{ +return __btrfs_lookup_bio_sums (root, inode, bio,0 , dst,0 ); +} + +int btrfs_lookup_bio_sums_dio (struct btrfs_root *root,struct inode *inode, +struct bio *bio,u64 offset,u32 *dst) +{ +return __btrfs_lookup_bio_sums (root, inode, bio, offset, dst,1 ); +} +int btrfs_lookup_csums_range (struct btrfs_root *root,u64 start,u64 end,struct list_head *list) {
fs/btrfs/inode.c +204 -1
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