On Mon, Mar 03, 2014 at 05:24:43PM +0800, Liu Bo wrote:
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -3972,6 +3972,7 @@ static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
> pgoff_t last_index;
> unsigned pg_offset = offset & ~PAGE_CACHE_MASK;
> ssize_t ret = 0;
> + struct file_ra_state *ra = NULL;
>
> key.objectid = sctx->cur_ino;
> key.type = BTRFS_INODE_ITEM_KEY;
> @@ -3991,6 +3992,17 @@ static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
> goto out;
>
> last_index = (offset + len - 1) >> PAGE_CACHE_SHIFT;
> +
> + /* initial readahead */
> + ra = kzalloc(sizeof(*ra), GFP_NOFS);
> + if (!ra) {
> + ret = -ENOMEM;
This should not be a hard failure, it can continue without RA for this
buffer. Besides, the RA buffer can be allocated at the beginning of send
operation and pointer stored in the send context.
> + goto out;
> + }
> +
> + file_ra_state_init(ra, inode->i_mapping);
> + btrfs_force_ra(inode->i_mapping, ra, NULL, index, last_index-index + 1);
> +
> while (index <= last_index) {
> unsigned cur_len = min_t(unsigned, len,
> PAGE_CACHE_SIZE - pg_offset);
> @@ -4022,6 +4034,7 @@ static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
> ret += cur_len;
> }
> out:
> + kfree(ra);
> iput(inode);
> return ret;
> }
> --
> 1.8.1.4
>
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