aboutsummaryrefslogtreecommitdiff
path: root/mm/filemap.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c31
1 files changed, 21 insertions, 10 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 9c7334bafda..648f2c0c8e1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2069,7 +2069,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
{
struct file *file = iocb->ki_filp;
struct address_space * mapping = file->f_mapping;
- struct address_space_operations *a_ops = mapping->a_ops;
+ const struct address_space_operations *a_ops = mapping->a_ops;
struct inode *inode = mapping->host;
long status = 0;
struct page *page;
@@ -2095,14 +2095,21 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
do {
unsigned long index;
unsigned long offset;
- unsigned long maxlen;
size_t copied;
offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
index = pos >> PAGE_CACHE_SHIFT;
bytes = PAGE_CACHE_SIZE - offset;
- if (bytes > count)
- bytes = count;
+
+ /* Limit the size of the copy to the caller's write size */
+ bytes = min(bytes, count);
+
+ /*
+ * Limit the size of the copy to that of the current segment,
+ * because fault_in_pages_readable() doesn't know how to walk
+ * segments.
+ */
+ bytes = min(bytes, cur_iov->iov_len - iov_base);
/*
* Bring in the user page that we will copy from _first_.
@@ -2110,10 +2117,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
* 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);
+ fault_in_pages_readable(buf, bytes);
page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
if (!page) {
@@ -2121,6 +2125,12 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
break;
}
+ if (unlikely(bytes == 0)) {
+ status = 0;
+ copied = 0;
+ goto zero_length_segment;
+ }
+
status = a_ops->prepare_write(file, page, offset, offset+bytes);
if (unlikely(status)) {
loff_t isize = i_size_read(inode);
@@ -2150,7 +2160,8 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
page_cache_release(page);
continue;
}
- if (likely(copied > 0)) {
+zero_length_segment:
+ if (likely(copied >= 0)) {
if (!status)
status = copied;
@@ -2215,7 +2226,7 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct file *file = iocb->ki_filp;
- struct address_space * mapping = file->f_mapping;
+ const struct address_space * mapping = file->f_mapping;
size_t ocount; /* original count */
size_t count; /* after file limit checks */
struct inode *inode = mapping->host;