NFS: Support multiple segment iovecs in the NFS direct I/O path

Allow applications to perform asynchronous scatter-gather direct I/O
to NFS files.

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>

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index e30d928..88d5d1c 100644 (file)
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -272,8 +272,6 @@ static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned lo
        int result;
        ssize_t started = 0;
 
-       get_dreq(dreq);
-
        do {
                struct nfs_read_data *data;
                size_t bytes;
@@ -347,11 +345,8 @@ static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned lo
                count -= bytes;
        } while (count != 0);
 
-       if (put_dreq(dreq))
-               nfs_direct_complete(dreq);
-
        if (started)
-               return 0;
+               return started;
        return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
@@ -390,7 +385,8 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
        return -EIO;
 }
 
-static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
+static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos)
 {
        ssize_t result = 0;
        sigset_t oldset;
@@ -407,9 +403,8 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
        if (!is_sync_kiocb(iocb))
                dreq->iocb = iocb;
 
-       nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
        rpc_clnt_sigmask(clnt, &oldset);
-       result = nfs_direct_read_schedule(dreq, user_addr, count, pos);
+       result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
        if (!result)
                result = nfs_direct_wait(dreq);
        rpc_clnt_sigunmask(clnt, &oldset);
@@ -645,8 +640,6 @@ static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned l
        int result;
        ssize_t started = 0;
 
-       get_dreq(dreq);
-
        do {
                struct nfs_write_data *data;
                size_t bytes;
@@ -724,11 +717,8 @@ static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned l
                count -= bytes;
        } while (count != 0);
 
-       if (put_dreq(dreq))
-               nfs_direct_write_complete(dreq, inode);
-
        if (started)
-               return 0;
+               return started;
        return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
@@ -768,7 +758,9 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
        return -EIO;
 }
 
-static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
+static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
+                               unsigned long nr_segs, loff_t pos,
+                               size_t count)
 {
        ssize_t result = 0;
        sigset_t oldset;
@@ -791,10 +783,8 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
        if (!is_sync_kiocb(iocb))
                dreq->iocb = iocb;
 
-       nfs_add_stats(inode, NFSIOS_DIRECTWRITTENBYTES, count);
-
        rpc_clnt_sigmask(clnt, &oldset);
-       result = nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
+       result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
        if (!result)
                result = nfs_direct_wait(dreq);
        rpc_clnt_sigunmask(clnt, &oldset);
@@ -830,21 +820,16 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
        ssize_t retval = -EINVAL;
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
-       /* XXX: temporary */
-       const char __user *buf = iov[0].iov_base;
-       size_t count = iov[0].iov_len;
+       size_t count;
+
+       count = iov_length(iov, nr_segs);
+       nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 
-       dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
+       dprintk("nfs: direct read(%s/%s, %zd@%Ld)\n",
                file->f_path.dentry->d_parent->d_name.name,
                file->f_path.dentry->d_name.name,
-               (unsigned long) count, (long long) pos);
+               count, (long long) pos);
 
-       if (nr_segs != 1)
-               goto out;
-
-       retval = -EFAULT;
-       if (!access_ok(VERIFY_WRITE, buf, count))
-               goto out;
        retval = 0;
        if (!count)
                goto out;
@@ -853,7 +838,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
        if (retval)
                goto out;
 
-       retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
+       retval = nfs_direct_read(iocb, iov, nr_segs, pos);
        if (retval > 0)
                iocb->ki_pos = pos + retval;
 
@@ -892,17 +877,15 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
        ssize_t retval = -EINVAL;
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
-       /* XXX: temporary */
-       const char __user *buf = iov[0].iov_base;
-       size_t count = iov[0].iov_len;
+       size_t count;
 
-       dprintk("nfs: direct write(%s/%s, %lu@%Ld)\n",
+       count = iov_length(iov, nr_segs);
+       nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
+
+       dfprintk(VFS, "nfs: direct write(%s/%s, %zd@%Ld)\n",
                file->f_path.dentry->d_parent->d_name.name,
                file->f_path.dentry->d_name.name,
-               (unsigned long) count, (long long) pos);
-
-       if (nr_segs != 1)
-               goto out;
+               count, (long long) pos);
 
        retval = generic_write_checks(file, &pos, &count, 0);
        if (retval)
@@ -915,15 +898,11 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
        if (!count)
                goto out;
 
-       retval = -EFAULT;
-       if (!access_ok(VERIFY_READ, buf, count))
-               goto out;
-
        retval = nfs_sync_mapping(mapping);
        if (retval)
                goto out;
 
-       retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
+       retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
 
        if (retval > 0)
                iocb->ki_pos = pos + retval;