cifs_iovec_read: keep iov_iter between the calls of cifs_readdata_to_iov()
... we are doing them on adjacent parts of file, so what happens is that
each subsequent call works to rebuild the iov_iter to exact state it
had been abandoned in by previous one. Just keep it through the entire
cifs_iovec_read(). And use copy_page_to_iter() instead of doing
kmap/copy_to_user/kunmap manually...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index df414db..ad63e47 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2727,56 +2727,27 @@
/**
* cifs_readdata_to_iov - copy data from pages in response to an iovec
* @rdata: the readdata response with list of pages holding data
- * @iov: vector in which we should copy the data
- * @nr_segs: number of segments in vector
- * @offset: offset into file of the first iovec
- * @copied: used to return the amount of data copied to the iov
+ * @iter: destination for our data
*
* This function copies data from a list of pages in a readdata response into
* an array of iovecs. It will first calculate where the data should go
* based on the info in the readdata and then copy the data into that spot.
*/
-static ssize_t
-cifs_readdata_to_iov(struct cifs_readdata *rdata, const struct iovec *iov,
- unsigned long nr_segs, loff_t offset, ssize_t *copied)
+static int
+cifs_readdata_to_iov(struct cifs_readdata *rdata, struct iov_iter *iter)
{
- int rc = 0;
- struct iov_iter ii;
- size_t pos = rdata->offset - offset;
- ssize_t remaining = rdata->bytes;
- unsigned char *pdata;
+ size_t remaining = rdata->bytes;
unsigned int i;
- /* set up iov_iter and advance to the correct offset */
- iov_iter_init(&ii, iov, nr_segs, iov_length(iov, nr_segs), 0);
- iov_iter_advance(&ii, pos);
-
- *copied = 0;
for (i = 0; i < rdata->nr_pages; i++) {
- ssize_t copy;
struct page *page = rdata->pages[i];
-
- /* copy a whole page or whatever's left */
- copy = min_t(ssize_t, remaining, PAGE_SIZE);
-
- /* ...but limit it to whatever space is left in the iov */
- copy = min_t(ssize_t, copy, iov_iter_count(&ii));
-
- /* go while there's data to be copied and no errors */
- if (copy && !rc) {
- pdata = kmap(page);
- rc = memcpy_toiovecend(ii.iov, pdata, ii.iov_offset,
- (int)copy);
- kunmap(page);
- if (!rc) {
- *copied += copy;
- remaining -= copy;
- iov_iter_advance(&ii, copy);
- }
- }
+ size_t copy = min(remaining, PAGE_SIZE);
+ size_t written = copy_page_to_iter(page, 0, copy, iter);
+ remaining -= written;
+ if (written < copy && iov_iter_count(iter) > 0)
+ break;
}
-
- return rc;
+ return remaining ? -EFAULT : 0;
}
static void
@@ -2851,6 +2822,7 @@
struct cifsFileInfo *open_file;
struct cifs_readdata *rdata, *tmp;
struct list_head rdata_list;
+ struct iov_iter to;
pid_t pid;
if (!nr_segs)
@@ -2860,6 +2832,8 @@
if (!len)
return 0;
+ iov_iter_init(&to, iov, nr_segs, len, 0);
+
INIT_LIST_HEAD(&rdata_list);
cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
open_file = file->private_data;
@@ -2917,12 +2891,11 @@
if (!list_empty(&rdata_list))
rc = 0;
+ len = iov_iter_count(&to);
/* the loop below should proceed in the order of increasing offsets */
list_for_each_entry_safe(rdata, tmp, &rdata_list, list) {
again:
if (!rc) {
- ssize_t copied;
-
/* FIXME: freezable sleep too? */
rc = wait_for_completion_killable(&rdata->done);
if (rc)
@@ -2935,10 +2908,7 @@
goto again;
}
} else {
- rc = cifs_readdata_to_iov(rdata, iov,
- nr_segs, *poffset,
- &copied);
- total_read += copied;
+ rc = cifs_readdata_to_iov(rdata, &to);
}
}
@@ -2946,6 +2916,8 @@
kref_put(&rdata->refcount, cifs_uncached_readdata_release);
}
+ total_read = len - iov_iter_count(&to);
+
cifs_stats_bytes_read(tcon, total_read);
*poffset += total_read;