NFS: Introduce iovec I/O helpers to fs/nfs/direct.c
Add helpers that iterate over multi-segment iovecs. These will be used to support multi-segment scatter/gather direct I/O in a later patch. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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@ -355,6 +355,41 @@ static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned lo
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return result < 0 ? (ssize_t) result : -EFAULT;
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}
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static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
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const struct iovec *iov,
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unsigned long nr_segs,
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loff_t pos)
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{
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ssize_t result = -EINVAL;
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size_t requested_bytes = 0;
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unsigned long seg;
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get_dreq(dreq);
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for (seg = 0; seg < nr_segs; seg++) {
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const struct iovec *vec = &iov[seg];
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result = nfs_direct_read_schedule(dreq,
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(unsigned long)vec->iov_base,
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vec->iov_len, pos);
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if (result < 0)
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break;
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requested_bytes += result;
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if ((size_t)result < vec->iov_len)
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break;
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pos += vec->iov_len;
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}
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if (put_dreq(dreq))
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nfs_direct_complete(dreq);
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if (requested_bytes != 0)
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return 0;
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if (result < 0)
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return result;
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return -EIO;
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}
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static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
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{
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ssize_t result = 0;
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@ -697,6 +732,42 @@ static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned l
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return result < 0 ? (ssize_t) result : -EFAULT;
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}
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static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
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const struct iovec *iov,
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unsigned long nr_segs,
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loff_t pos, int sync)
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{
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ssize_t result = 0;
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size_t requested_bytes = 0;
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unsigned long seg;
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get_dreq(dreq);
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for (seg = 0; seg < nr_segs; seg++) {
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const struct iovec *vec = &iov[seg];
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result = nfs_direct_write_schedule(dreq,
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(unsigned long)vec->iov_base,
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vec->iov_len,
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pos, sync);
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if (result < 0)
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break;
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requested_bytes += result;
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if ((size_t)result < vec->iov_len)
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break;
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pos += vec->iov_len;
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}
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if (put_dreq(dreq))
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nfs_direct_write_complete(dreq, dreq->inode);
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if (requested_bytes != 0)
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return 0;
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if (result < 0)
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return result;
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return -EIO;
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}
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static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
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{
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ssize_t result = 0;
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