NFS: use generic_write_checks() to sanity check direct writes

 Replace ad hoc write parameter sanity checking in nfs_file_direct_write()
 with a call to generic_write_checks().  This should make the proper checks
 modulo the O_LARGEFILE flag, and should catch NFSv2-specific limitations by
 virtue of i_sb->s_maxbytes.

 Test plan:
 Posix compliance testing with both NFSv2 and NFSv3.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 19 insertions, 24 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index ae2be0744191..f69d95aa78b2 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -660,10 +660,10 @@ nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t
                 .iov_len = count,
         };
 
-        dprintk("nfs: direct read(%s/%s, %lu@%lu)\n",
+        dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
                 file->f_dentry->d_parent->d_name.name,
                 file->f_dentry->d_name.name,
-                (unsigned long) count, (unsigned long) pos);
+                (unsigned long) count, (long long) pos);
 
         if (!is_sync_kiocb(iocb))
                 goto out;
@@ -716,9 +716,7 @@ out:
 ssize_t
 nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos)
 {
-        ssize_t retval = -EINVAL;
-        loff_t *ppos = &iocb->ki_pos;
-        unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+        ssize_t retval;
         struct file *file = iocb->ki_filp;
         struct nfs_open_context *ctx =
                         (struct nfs_open_context *) file->private_data;
@@ -726,35 +724,32 @@ nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count,
         struct inode *inode = mapping->host;
         struct iovec iov = {
                 .iov_base = (char __user *)buf,
-                .iov_len = count,
         };
 
-        dfprintk(VFS, "nfs: direct write(%s/%s(%ld), %lu@%lu)\n",
+        dfprintk(VFS, "nfs: direct write(%s/%s, %lu@%Ld)\n",
                 file->f_dentry->d_parent->d_name.name,
-                file->f_dentry->d_name.name, inode->i_ino,
-                (unsigned long) count, (unsigned long) pos);
+                file->f_dentry->d_name.name,
+                (unsigned long) count, (long long) pos);
 
+        retval = -EINVAL;
         if (!is_sync_kiocb(iocb))
                 goto out;
-        if (count < 0)
-                goto out;
-        if (pos < 0)
+
+        retval = generic_write_checks(file, &pos, &count, 0);
+        if (retval)
                 goto out;
-        retval = -EFAULT;
-        if (!access_ok(VERIFY_READ, iov.iov_base, iov.iov_len))
+
+        retval = -EINVAL;
+        if ((ssize_t) count < 0)
                 goto out;
-        retval = -EFBIG;
-        if (limit != RLIM_INFINITY) {
-                if (pos >= limit) {
-                        send_sig(SIGXFSZ, current, 0);
-                        goto out;
-                }
-                if (count > limit - (unsigned long) pos)
-                        count = limit - (unsigned long) pos;
-        }
         retval = 0;
         if (!count)
                 goto out;
+        iov.iov_len = count,
+
+        retval = -EFAULT;
+        if (!access_ok(VERIFY_READ, iov.iov_base, iov.iov_len))
+                goto out;
 
         retval = nfs_sync_mapping(mapping);
         if (retval)
@@ -764,7 +759,7 @@ nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count,
         if (mapping->nrpages)
                 invalidate_inode_pages2(mapping);
         if (retval > 0)
-                *ppos = pos + retval;
+                iocb->ki_pos = pos + retval;
 
 out:
         return retval;