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authorAl Viro <viro@zeniv.linux.org.uk>2014-03-19 01:16:16 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-05-06 17:32:52 -0400
commitf67da30c1d5fc9e341bc8121708874bfd7b31e45 (patch)
tree504966ed27e82dbcbe31786c9a0851a4ae79ef3e
parent5b46f25ddc6edf4adff1a137d453da542c27a640 (diff)
new helper: iov_iter_npages()
counts the pages covered by iov_iter, up to given limit. do_block_direct_io() and fuse_iter_npages() switched to it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/direct-io.c9
-rw-r--r--fs/fuse/file.c16
-rw-r--r--include/linux/uio.h1
-rw-r--r--mm/iov_iter.c27
4 files changed, 31 insertions, 22 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 4b410d58faa..98040ba388a 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1100,7 +1100,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
get_block_t get_block, dio_iodone_t end_io,
dio_submit_t submit_io, int flags)
{
- int seg;
unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
unsigned blkbits = i_blkbits;
unsigned blocksize_mask = (1 << blkbits) - 1;
@@ -1108,7 +1107,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
loff_t end = offset + iov_iter_count(iter);
struct dio *dio;
struct dio_submit sdio = { 0, };
- unsigned long user_addr;
struct buffer_head map_bh = { 0, };
struct blk_plug plug;
unsigned long align = offset | iov_iter_alignment(iter);
@@ -1231,12 +1229,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
if (unlikely(sdio.blkfactor))
sdio.pages_in_io = 2;
- for (seg = 0; seg < iter->nr_segs; seg++) {
- user_addr = (unsigned long)iter->iov[seg].iov_base;
- sdio.pages_in_io +=
- ((user_addr + iter->iov[seg].iov_len + PAGE_SIZE-1) /
- PAGE_SIZE - user_addr / PAGE_SIZE);
- }
+ sdio.pages_in_io += iov_iter_npages(iter, INT_MAX);
blk_start_plug(&plug);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 7db564d18dc..7026014717b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1310,7 +1310,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
unsigned npages;
- size_t start, end, frag_size;
+ size_t start;
unsigned n = req->max_pages - req->num_pages;
ssize_t ret = iov_iter_get_pages(ii,
&req->pages[req->num_pages],
@@ -1344,19 +1344,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
static inline int fuse_iter_npages(const struct iov_iter *ii_p)
{
- struct iov_iter ii = *ii_p;
- int npages = 0;
-
- while (iov_iter_count(&ii) && npages < FUSE_MAX_PAGES_PER_REQ) {
- unsigned long user_addr = fuse_get_user_addr(&ii);
- unsigned offset = user_addr & ~PAGE_MASK;
- size_t frag_size = iov_iter_single_seg_count(&ii);
-
- npages += (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
- iov_iter_advance(&ii, frag_size);
- }
-
- return min(npages, FUSE_MAX_PAGES_PER_REQ);
+ return iov_iter_npages(ii_p, FUSE_MAX_PAGES_PER_REQ);
}
ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 341986116d8..2f8825b0668 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -73,6 +73,7 @@ void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
unsigned long nr_segs, size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
size_t maxsize, size_t *start);
+int iov_iter_npages(const struct iov_iter *i, int maxpages);
static inline size_t iov_iter_count(struct iov_iter *i)
{
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 45204cd5ccd..0b677f8f9ba 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -262,3 +262,30 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
return (res == n ? len : res * PAGE_SIZE) - *start;
}
EXPORT_SYMBOL(iov_iter_get_pages);
+
+int iov_iter_npages(const struct iov_iter *i, int maxpages)
+{
+ size_t offset = i->iov_offset;
+ size_t size = i->count;
+ const struct iovec *iov = i->iov;
+ int npages = 0;
+ int n;
+
+ for (n = 0; size && n < i->nr_segs; n++, iov++) {
+ unsigned long addr = (unsigned long)iov->iov_base + offset;
+ size_t len = iov->iov_len - offset;
+ offset = 0;
+ if (unlikely(!len)) /* empty segment */
+ continue;
+ if (len > size)
+ len = size;
+ npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE
+ - addr / PAGE_SIZE;
+ if (npages >= maxpages) /* don't bother going further */
+ return maxpages;
+ size -= len;
+ offset = 0;
+ }
+ return min(npages, maxpages);
+}
+EXPORT_SYMBOL(iov_iter_npages);