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authorAl Viro <viro@zeniv.linux.org.uk>2014-03-21 04:58:33 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-05-06 17:32:53 -0400
commit91f79c43d1b54d7154b118860d81b39bad07dfff (patch)
treea5b142ba57fdabf835476b6dbca24288a78f0c53 /mm/iov_iter.c
parentf67da30c1d5fc9e341bc8121708874bfd7b31e45 (diff)
downloadlinux-91f79c43d1b54d7154b118860d81b39bad07dfff.tar.bz2
new helper: iov_iter_get_pages_alloc()
same as iov_iter_get_pages(), except that pages array is allocated (kmalloc if possible, vmalloc if that fails) and left for caller to free. Lustre and NFS ->direct_IO() switched to it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'mm/iov_iter.c')
-rw-r--r--mm/iov_iter.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 0b677f8f9bad..a5c691c1a283 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -1,6 +1,8 @@
#include <linux/export.h>
#include <linux/uio.h>
#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
@@ -263,6 +265,44 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
}
EXPORT_SYMBOL(iov_iter_get_pages);
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+ struct page ***pages, size_t maxsize,
+ size_t *start)
+{
+ size_t offset = i->iov_offset;
+ const struct iovec *iov = i->iov;
+ size_t len;
+ unsigned long addr;
+ void *p;
+ int n;
+ int res;
+
+ len = iov->iov_len - offset;
+ if (len > i->count)
+ len = i->count;
+ if (len > maxsize)
+ len = maxsize;
+ addr = (unsigned long)iov->iov_base + offset;
+ len += *start = addr & (PAGE_SIZE - 1);
+ addr &= ~(PAGE_SIZE - 1);
+ n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
+
+ p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
+ if (!p)
+ p = vmalloc(n * sizeof(struct page *));
+ if (!p)
+ return -ENOMEM;
+
+ res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
+ if (unlikely(res < 0)) {
+ kvfree(p);
+ return res;
+ }
+ *pages = p;
+ return (res == n ? len : res * PAGE_SIZE) - *start;
+}
+EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
size_t offset = i->iov_offset;