1 files changed, 33 insertions, 58 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index db76cec3ce21..45e34908bdb5 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -34,6 +34,7 @@
 #include <linux/security.h>
 #include <linux/magic.h>
 #include <linux/migrate.h>
+#include <linux/uio.h>
 
 #include <asm/uaccess.h>
 
@@ -179,42 +180,33 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 }
 #endif
 
-static int
+static size_t
 hugetlbfs_read_actor(struct page *page, unsigned long offset,
-                        char __user *buf, unsigned long count,
-                        unsigned long size)
+                        struct iov_iter *to, unsigned long size)
 {
-        char *kaddr;
-        unsigned long left, copied = 0;
+        size_t copied = 0;
         int i, chunksize;
 
-        if (size > count)
-                size = count;
-
         /* Find which 4k chunk and offset with in that chunk */
         i = offset >> PAGE_CACHE_SHIFT;
         offset = offset & ~PAGE_CACHE_MASK;
 
         while (size) {
+                size_t n;
                 chunksize = PAGE_CACHE_SIZE;
                 if (offset)
                         chunksize -= offset;
                 if (chunksize > size)
                         chunksize = size;
-                kaddr = kmap(&page[i]);
-                left = __copy_to_user(buf, kaddr + offset, chunksize);
-                kunmap(&page[i]);
-                if (left) {
-                        copied += (chunksize - left);
-                        break;
-                }
+                n = copy_page_to_iter(&page[i], offset, chunksize, to);
+                copied += n;
+                if (n != chunksize)
+                        return copied;
                 offset = 0;
                 size -= chunksize;
-                buf += chunksize;
-                copied += chunksize;
                 i++;
         }
-        return copied ? copied : -EFAULT;
+        return copied;
 }
 
 /*
@@ -222,39 +214,34 @@ hugetlbfs_read_actor(struct page *page, unsigned long offset,
  * data. Its *very* similar to do_generic_mapping_read(), we can't use that
  * since it has PAGE_CACHE_SIZE assumptions.
  */
-static ssize_t hugetlbfs_read(struct file *filp, char __user *buf,
-                              size_t len, loff_t *ppos)
+static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-        struct hstate *h = hstate_file(filp);
-        struct address_space *mapping = filp->f_mapping;
+        struct file *file = iocb->ki_filp;
+        struct hstate *h = hstate_file(file);
+        struct address_space *mapping = file->f_mapping;
         struct inode *inode = mapping->host;
-        unsigned long index = *ppos >> huge_page_shift(h);
-        unsigned long offset = *ppos & ~huge_page_mask(h);
+        unsigned long index = iocb->ki_pos >> huge_page_shift(h);
+        unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
         unsigned long end_index;
         loff_t isize;
         ssize_t retval = 0;
 
-        /* validate length */
-        if (len == 0)
-                goto out;
-
-        for (;;) {
+        while (iov_iter_count(to)) {
                 struct page *page;
-                unsigned long nr, ret;
-                int ra;
+                size_t nr, copied;
 
                 /* nr is the maximum number of bytes to copy from this page */
                 nr = huge_page_size(h);
                 isize = i_size_read(inode);
                 if (!isize)
-                        goto out;
+                        break;
                 end_index = (isize - 1) >> huge_page_shift(h);
-                if (index >= end_index) {
-                        if (index > end_index)
-                                goto out;
+                if (index > end_index)
+                        break;
+                if (index == end_index) {
                         nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
                         if (nr <= offset)
-                                goto out;
+                                break;
                 }
                 nr = nr - offset;
 
@@ -265,39 +252,27 @@ static ssize_t hugetlbfs_read(struct file *filp, char __user *buf,
                          * We have a HOLE, zero out the user-buffer for the
                          * length of the hole or request.
                          */
-                        ret = len < nr ? len : nr;
-                        if (clear_user(buf, ret))
-                                ra = -EFAULT;
-                        else
-                                ra = 0;
+                        copied = iov_iter_zero(nr, to);
                 } else {
                         unlock_page(page);
 
                         /*
                          * We have the page, copy it to user space buffer.
                          */
-                        ra = hugetlbfs_read_actor(page, offset, buf, len, nr);
-                        ret = ra;
+                        copied = hugetlbfs_read_actor(page, offset, to, nr);
                         page_cache_release(page);
                 }
-                if (ra < 0) {
-                        if (retval == 0)
-                                retval = ra;
-                        goto out;
+                offset += copied;
+                retval += copied;
+                if (copied != nr && iov_iter_count(to)) {
+                        if (!retval)
+                                retval = -EFAULT;
+                        break;
                 }
-
-                offset += ret;
-                retval += ret;
-                len -= ret;
                 index += offset >> huge_page_shift(h);
                 offset &= ~huge_page_mask(h);
-
-                /* short read or no more work */
-                if ((ret != nr) || (len == 0))
-                        break;
         }
-out:
-        *ppos = ((loff_t)index << huge_page_shift(h)) + offset;
+        iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
         return retval;
 }
 
@@ -721,7 +696,7 @@ static void init_once(void *foo)
 }
 
 const struct file_operations hugetlbfs_file_operations = {
-        .read                   = hugetlbfs_read,
+        .read_iter              = hugetlbfs_read_iter,
         .mmap                   = hugetlbfs_file_mmap,
         .fsync                  = noop_fsync,
         .get_unmapped_area      = hugetlb_get_unmapped_area,