new helper: iov_iter_npages()

counts the pages covered by iov_iter, up to given limit.
do_block_direct_io() and fuse_iter_npages() switched to
it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 8 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 4b410d58faae..98040ba388ac 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1100,7 +1100,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         get_block_t get_block, dio_iodone_t end_io,
         dio_submit_t submit_io, int flags)
 {
-        int seg;
         unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
         unsigned blkbits = i_blkbits;
         unsigned blocksize_mask = (1 << blkbits) - 1;
@@ -1108,7 +1107,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         loff_t end = offset + iov_iter_count(iter);
         struct dio *dio;
         struct dio_submit sdio = { 0, };
-        unsigned long user_addr;
         struct buffer_head map_bh = { 0, };
         struct blk_plug plug;
         unsigned long align = offset | iov_iter_alignment(iter);
@@ -1231,12 +1229,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         if (unlikely(sdio.blkfactor))
                 sdio.pages_in_io = 2;
 
-        for (seg = 0; seg < iter->nr_segs; seg++) {
-                user_addr = (unsigned long)iter->iov[seg].iov_base;
-                sdio.pages_in_io +=
-                        ((user_addr + iter->iov[seg].iov_len + PAGE_SIZE-1) /
-                                PAGE_SIZE - user_addr / PAGE_SIZE);
-        }
+        sdio.pages_in_io += iov_iter_npages(iter, INT_MAX);
 
         blk_start_plug(&plug);