Great, I'll test this and the others overnight. Thanks!
-chris
Excerpts from Miao Xie's message of 2010-11-21 22:04:43 -0500:
> V1->V2 Changes:
> change the fix method. we split bios in btrfs_submit_direct() to fix this
> problem now.
>
> btrfs paniced when we write >64KB data by direct IO at one time.
>
> Reproduce steps:
> # mkfs.btrfs /dev/sda5 /dev/sda6
> # mount /dev/sda5 /mnt
> # dd if=/dev/zero of=/mnt/tmpfile bs=100K count=1 oflag=direct
>
> Then btrfs paniced:
> mapping failed logical 1103155200 bio len 69632 len 12288
> ------------[ cut here ]------------
> kernel BUG at fs/btrfs/volumes.c:3010!
> [SNIP]
> Pid: 1992, comm: btrfs-worker-0 Not tainted 2.6.37-rc1 #1 D2399/PRIMERGY
> RIP: 0010:[<ffffffffa03d1462>] [<ffffffffa03d1462>] btrfs_map_bio+0x202/0x210 [btrfs]
> [SNIP]
> Call Trace:
> [<ffffffffa03ab3eb>] __btrfs_submit_bio_done+0x1b/0x20 [btrfs]
> [<ffffffffa03a35ff>] run_one_async_done+0x9f/0xb0 [btrfs]
> [<ffffffffa03d3d20>] run_ordered_completions+0x80/0xc0 [btrfs]
> [<ffffffffa03d45a4>] worker_loop+0x154/0x5f0 [btrfs]
> [<ffffffffa03d4450>] ? worker_loop+0x0/0x5f0 [btrfs]
> [<ffffffffa03d4450>] ? worker_loop+0x0/0x5f0 [btrfs]
> [<ffffffff81083216>] kthread+0x96/0xa0
> [<ffffffff8100cec4>] kernel_thread_helper+0x4/0x10
> [<ffffffff81083180>] ? kthread+0x0/0xa0
> [<ffffffff8100cec0>] ? kernel_thread_helper+0x0/0x10
>
> We fix this problem by splitting bios when we submit bios.
>
> Reported-by: Tsutomu Itoh <t-itoh@xxxxxxxxxxxxxx>
> Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> Tested-by: Tsutomu Itoh <t-itoh@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/inode.c | 205 ++++++++++++++++++++++++++++++++++++++++++++++++------
> 1 files changed, 184 insertions(+), 21 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 5a5edc7..c91d0e3 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5535,13 +5535,21 @@ struct btrfs_dio_private {
> u64 bytes;
> u32 *csums;
> void *private;
> +
> + /* number of bios pending for this dio */
> + atomic_t pending_bios;
> +
> + /* IO errors */
> + int errors;
> +
> + struct bio *orig_bio;
> };
>
> static void btrfs_endio_direct_read(struct bio *bio, int err)
> {
> + struct btrfs_dio_private *dip = bio->bi_private;
> struct bio_vec *bvec_end = bio->bi_io_vec + bio->bi_vcnt - 1;
> struct bio_vec *bvec = bio->bi_io_vec;
> - struct btrfs_dio_private *dip = bio->bi_private;
> struct inode *inode = dip->inode;
> struct btrfs_root *root = BTRFS_I(inode)->root;
> u64 start;
> @@ -5684,6 +5692,176 @@ static int __btrfs_submit_bio_start_direct_io(struct inode *inode, int rw,
> return 0;
> }
>
> +static void btrfs_end_dio_bio(struct bio *bio, int err)
> +{
> + struct btrfs_dio_private *dip = bio->bi_private;
> +
> + if (err) {
> + printk(KERN_ERR "btrfs direct IO failed ino %lu rw %lu "
> + "disk_bytenr %lu len %u err no %d\n",
> + dip->inode->i_ino, bio->bi_rw, bio->bi_sector,
> + bio->bi_size, err);
> + dip->errors = 1;
> +
> + /*
> + * before atomic variable goto zero, we must make sure
> + * dip->errors is perceived to be set.
> + */
> + smp_mb__before_atomic_dec();
> + }
> +
> + /* if there are more bios still pending for this dio, just exit */
> + if (!atomic_dec_and_test(&dip->pending_bios))
> + goto out;
> +
> + if (dip->errors)
> + bio_io_error(dip->orig_bio);
> + else {
> + set_bit(BIO_UPTODATE, &dip->orig_bio->bi_flags);
> + bio_endio(dip->orig_bio, 0);
> + }
> +out:
> + bio_put(bio);
> +}
> +
> +static struct bio *btrfs_dio_bio_alloc(struct block_device *bdev,
> + u64 first_sector, gfp_t gfp_flags)
> +{
> + int nr_vecs = bio_get_nr_vecs(bdev);
> + return btrfs_bio_alloc(bdev, first_sector, nr_vecs, gfp_flags);
> +}
> +
> +static inline int __btrfs_submit_dio_bio(struct bio *bio, struct inode *inode,
> + int rw, u64 file_offset, int skip_sum,
> + u32 *csums)
> +{
> + int write = rw & REQ_WRITE;
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + int ret;
> +
> + bio_get(bio);
> + ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
> + if (ret)
> + goto err;
> +
> + if (write && !skip_sum) {
> + ret = btrfs_wq_submit_bio(root->fs_info,
> + inode, rw, bio, 0, 0,
> + file_offset,
> + __btrfs_submit_bio_start_direct_io,
> + __btrfs_submit_bio_done);
> + goto err;
> + } else if (!skip_sum)
> + btrfs_lookup_bio_sums_dio(root, inode, bio,
> + file_offset, csums);
> +
> + ret = btrfs_map_bio(root, rw, bio, 0, 1);
> +err:
> + bio_put(bio);
> + return ret;
> +}
> +
> +static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip,
> + int skip_sum)
> +{
> + struct inode *inode = dip->inode;
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
> + struct bio *bio;
> + struct bio *orig_bio = dip->orig_bio;
> + struct bio_vec *bvec = orig_bio->bi_io_vec;
> + u64 start_sector = orig_bio->bi_sector;
> + u64 file_offset = dip->logical_offset;
> + u64 submit_len = 0;
> + u64 map_length;
> + int nr_pages = 0;
> + u32 *csums = dip->csums;
> + int ret = 0;
> +
> + bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, start_sector, GFP_NOFS);
> + if (!bio)
> + return -ENOMEM;
> + bio->bi_private = dip;
> + bio->bi_end_io = btrfs_end_dio_bio;
> + atomic_inc(&dip->pending_bios);
> +
> + map_length = orig_bio->bi_size;
> + ret = btrfs_map_block(map_tree, READ, start_sector << 9,
> + &map_length, NULL, 0);
> + if (ret) {
> + bio_put(bio);
> + return -EIO;
> + }
> +
> + while (bvec <= (orig_bio->bi_io_vec + orig_bio->bi_vcnt - 1)) {
> + if (unlikely(map_length < submit_len + bvec->bv_len ||
> + bio_add_page(bio, bvec->bv_page, bvec->bv_len,
> + bvec->bv_offset) < bvec->bv_len)) {
> + /*
> + * inc the count before we submit the bio so
> + * we know the end IO handler won't happen before
> + * we inc the count. Otherwise, the dip might get freed
> + * before we're done setting it up
> + */
> + atomic_inc(&dip->pending_bios);
> + ret = __btrfs_submit_dio_bio(bio, inode, rw,
> + file_offset, skip_sum,
> + csums);
> + if (ret) {
> + bio_put(bio);
> + atomic_dec(&dip->pending_bios);
> + goto out_err;
> + }
> +
> + if (!skip_sum)
> + csums = csums + nr_pages;
> + start_sector += submit_len >> 9;
> + file_offset += submit_len;
> +
> + submit_len = 0;
> + nr_pages = 0;
> +
> + bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev,
> + start_sector, GFP_NOFS);
> + if (!bio)
> + goto out_err;
> + bio->bi_private = dip;
> + bio->bi_end_io = btrfs_end_dio_bio;
> +
> + map_length = orig_bio->bi_size;
> + ret = btrfs_map_block(map_tree, READ, start_sector << 9,
> + &map_length, NULL, 0);
> + if (ret) {
> + bio_put(bio);
> + goto out_err;
> + }
> + } else {
> + submit_len += bvec->bv_len;
> + nr_pages ++;
> + bvec++;
> + }
> + }
> +
> + ret = __btrfs_submit_dio_bio(bio, inode, rw, file_offset, skip_sum,
> + csums);
> + if (!ret)
> + return 0;
> +
> + bio_put(bio);
> +out_err:
> + dip->errors = 1;
> + /*
> + * before atomic variable goto zero, we must
> + * make sure dip->errors is perceived to be set.
> + */
> + smp_mb__before_atomic_dec();
> + if (atomic_dec_and_test(&dip->pending_bios))
> + bio_io_error(dip->orig_bio);
> +
> + /* bio_end_io() will handle error, so we needn't return it */
> + return 0;
> +}
> +
> static void btrfs_submit_direct(int rw, struct bio *bio, struct inode *inode,
> loff_t file_offset)
> {
> @@ -5723,33 +5901,18 @@ static void btrfs_submit_direct(int rw, struct bio *bio, struct inode *inode,
>
> dip->disk_bytenr = (u64)bio->bi_sector << 9;
> bio->bi_private = dip;
> + dip->errors = 0;
> + dip->orig_bio = bio;
> + atomic_set(&dip->pending_bios, 0);
>
> if (write)
> bio->bi_end_io = btrfs_endio_direct_write;
> else
> bio->bi_end_io = btrfs_endio_direct_read;
>
> - ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
> - if (ret)
> - goto free_ordered;
> -
> - if (write && !skip_sum) {
> - ret = btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
> - inode, rw, bio, 0, 0,
> - dip->logical_offset,
> - __btrfs_submit_bio_start_direct_io,
> - __btrfs_submit_bio_done);
> - if (ret)
> - goto free_ordered;
> + ret = btrfs_submit_direct_hook(rw, dip, skip_sum);
> + if (!ret)
> return;
> - } else if (!skip_sum)
> - btrfs_lookup_bio_sums_dio(root, inode, bio,
> - dip->logical_offset, dip->csums);
> -
> - ret = btrfs_map_bio(root, rw, bio, 0, 1);
> - if (ret)
> - goto free_ordered;
> - return;
> free_ordered:
> /*
> * If this is a write, we need to clean up the reserved space and kill
--
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