[patch 3/6] generic_file_buffered_write() cleanup

Andrew Morton
2006-10-11T06:17:59Z

Signed-off-by: Andrew Morton <akpm@osdl.org>
---

mm/filemap.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)

diff -puN mm/filemap.c~generic_file_buffered_write-cleanup mm/filemap.c
--- a/mm/filemap.c~generic_file_buffered_write-cleanup
+++ a/mm/filemap.c
@@ -2064,16 +2064,15 @@ generic_file_buffered_write(struct kiocb
size_t count, ssize_t written)
{
struct file *file = iocb->ki_filp;
- struct address_space * mapping = file->f_mapping;
+ struct address_space *mapping = file->f_mapping;
const struct address_space_operations *a_ops = mapping->a_ops;
struct inode *inode = mapping->host;
long status = 0;
struct page *page;
struct page *cached_page = NULL;
- size_t bytes;
struct pagevec lru_pvec;
const struct iovec *cur_iov = iov; /* current iovec */
- size_t iov_base = 0; /* offset in the current iovec */
+ size_t iov_offset = 0; /* offset in the current iovec */
char __user *buf;

pagevec_init(&lru_pvec, 0);
@@ -2084,31 +2083,33 @@ generic_file_buffered_write(struct kiocb
if (likely(nr_segs == 1))
buf = iov->iov_base + written;
else {
- filemap_set_next_iovec(&cur_iov, &iov_base, written);
- buf = cur_iov->iov_base + iov_base;
+ filemap_set_next_iovec(&cur_iov, &iov_offset, written);
+ buf = cur_iov->iov_base + iov_offset;
}

do {
- unsigned long index;
- unsigned long offset;
- unsigned long maxlen;
- size_t copied;
+ pgoff_t index; /* Pagecache index for current page */
+ unsigned long offset; /* Offset into pagecache page */
+ unsigned long maxlen; /* Bytes remaining in current iovec */
+ size_t bytes; /* Bytes to write to page */
+ size_t copied; /* Bytes copied from user */

- offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
+ offset = (pos & (PAGE_CACHE_SIZE - 1));
index = pos >> PAGE_CACHE_SHIFT;
bytes = PAGE_CACHE_SIZE - offset;
if (bytes > count)
bytes = count;

+ maxlen = cur_iov->iov_len - iov_offset;
+ if (maxlen > bytes)
+ maxlen = bytes;
+
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
* same page as we're writing to, without it being marked
* up-to-date.
*/
- maxlen = cur_iov->iov_len - iov_base;
- if (maxlen > bytes)
- maxlen = bytes;
fault_in_pages_readable(buf, maxlen);

page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
@@ -2139,7 +2140,7 @@ generic_file_buffered_write(struct kiocb
buf, bytes);
else
copied = filemap_copy_from_user_iovec(page, offset,
- cur_iov, iov_base, bytes);
+ cur_iov, iov_offset, bytes);
flush_dcache_page(page);
status = a_ops->commit_write(file, page, offset, offset+bytes);
if (status == AOP_TRUNCATED_PAGE) {
@@ -2157,12 +2158,12 @@ generic_file_buffered_write(struct kiocb
buf += status;
if (unlikely(nr_segs > 1)) {
filemap_set_next_iovec(&cur_iov,
- &iov_base, status);
+ &iov_offset, status);
if (count)
buf = cur_iov->iov_base +
- iov_base;
+ iov_offset;
} else {
- iov_base += status;
+ iov_offset += status;
}
}
}
_