mm: write iovec cleanup

Hide some of the open-coded nr_segs tests into the iovec helpers.  This is all
to simplify generic_file_buffered_write, because that gets more complex in the
next patch.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index fb4c1c0..c59d5b3 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1823,12 +1823,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
        /*
         * handle partial DIO write.  Adjust cur_iov if needed.
         */
-       if (likely(nr_segs == 1))
-               buf = iov->iov_base + written;
-       else {
-               filemap_set_next_iovec(&cur_iov, &iov_offset, written);
-               buf = cur_iov->iov_base + iov_offset;
-       }
+       filemap_set_next_iovec(&cur_iov, nr_segs, &iov_offset, written);
 
        do {
                struct page *page;
@@ -1838,6 +1833,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                size_t bytes;           /* Bytes to write to page */
                size_t copied;          /* Bytes copied from user */
 
+               buf = cur_iov->iov_base + iov_offset;
                offset = (pos & (PAGE_CACHE_SIZE - 1));
                index = pos >> PAGE_CACHE_SHIFT;
                bytes = PAGE_CACHE_SIZE - offset;
@@ -1869,13 +1865,10 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                if (unlikely(status))
                        goto fs_write_aop_error;
 
-               if (likely(nr_segs == 1))
-                       copied = filemap_copy_from_user(page, offset,
-                                                       buf, bytes);
-               else
-                       copied = filemap_copy_from_user_iovec(page, offset,
-                                               cur_iov, iov_offset, bytes);
+               copied = filemap_copy_from_user(page, offset,
+                                       cur_iov, nr_segs, iov_offset, bytes);
                flush_dcache_page(page);
+
                status = a_ops->commit_write(file, page, offset, offset+bytes);
                if (unlikely(status < 0 || status == AOP_TRUNCATED_PAGE))
                        goto fs_write_aop_error;
@@ -1886,20 +1879,11 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                if (unlikely(status > 0)) /* filesystem did partial write */
                        copied = status;
 
-               if (likely(copied > 0)) {
-                       written += copied;
-                       count -= copied;
-                       pos += copied;
-                       buf += copied;
-                       if (unlikely(nr_segs > 1)) {
-                               filemap_set_next_iovec(&cur_iov,
-                                               &iov_offset, copied);
-                               if (count)
-                                       buf = cur_iov->iov_base + iov_offset;
-                       } else {
-                               iov_offset += copied;
-                       }
-               }
+               written += copied;
+               count -= copied;
+               pos += copied;
+               filemap_set_next_iovec(&cur_iov, nr_segs, &iov_offset, copied);
+
                unlock_page(page);
                mark_page_accessed(page);
                page_cache_release(page);

diff --cc mm/filemap.h
Simple merge

diff --cc mm/filemap_xip.c
Simple merge