[Devel] [PATCH rh7 1/4] ploop: Teach dio_sync_io() work with many pages

[Kirill Tkhai]

This will be used to submit bunch of pages in next patches.

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 drivers/block/ploop/io_direct.c |   42 ++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
index 1beb4f3292a2..5b56fc59da07 100644
--- a/drivers/block/ploop/io_direct.c
+++ b/drivers/block/ploop/io_direct.c
@@ -1149,12 +1149,17 @@ dio_make_io(struct ploop_io *io, int rw, struct page 
*page,
        return err;
 }
 
+/*
+ * @off is offset within first page in bytes.
+ * @len is sum length in bytes.
+ */
 static int
-dio_sync_io(struct ploop_io *io, int rw, struct page *page,
-           unsigned int len, unsigned int off, sector_t sec)
+dio_sync_io(struct ploop_io *io, int rw, struct page **pages,
+           int nr_pages, unsigned int len,
+           unsigned int off, sector_t sec)
 {
+       int i, count, nr_bios = 0, ret = 0;
        struct dio_comp comp;
-       int nr_bios;
 
        BUG_ON((len & 511) || (off & 511));
 
@@ -1166,36 +1171,53 @@ dio_sync_io(struct ploop_io *io, int rw, struct page 
*page,
        init_completion(&comp.comp);
        comp.error = 0;
 
-       nr_bios = dio_make_io(io, rw, page, len, off, sec,
-                             dio_endio_sync, &comp);
-       if (nr_bios < 0)
-               return nr_bios;
+       for (i = 0; i < nr_pages; i++) {
+               count = PAGE_SIZE - off;
+               if (count > len)
+                       count = len;
+
+               ret = dio_make_io(io, rw, pages[i], count, off, sec,
+                                     dio_endio_sync, &comp);
+               if (ret < 0)
+                       goto sub_and_wait;
+               nr_bios += ret;
+               sec += (count >> 9);
+               len -= count;
+               off = 0;
+       }
+
+       if (WARN_ON_ONCE(len))
+               ret = -EIO;
 
+sub_and_wait:
        if (atomic_sub_and_test(INT_MAX - nr_bios, &comp.count))
                complete(&comp.comp);
 
        wait_for_completion(&comp.comp);
 
-       return comp.error;
+       return ret < 0 ? ret : comp.error;
 }
 
 static int
 dio_sync_read(struct ploop_io * io, struct page * page, unsigned int len,
              unsigned int off, sector_t pos)
 {
-       return dio_sync_io(io, READ_SYNC, page, len, off, pos);
+       struct page *pages[] = { page };
+
+       return dio_sync_io(io, READ_SYNC, pages, 1, len, off, pos);
 }
 
 static int
 dio_sync_write(struct ploop_io * io, struct page * page, unsigned int len,
               unsigned int off, sector_t sec)
 {
+       struct page *pages[] = { page };
        int err;
 
        if (!(io->files.file->f_mode & FMODE_WRITE))
                return -EBADF;
 
-       err = dio_sync_io(io, WRITE_SYNC, page, len, off, sec);
+       err = dio_sync_io(io, WRITE_SYNC, pages, 1, len, off, sec);
 
        if (sec < io->plo->track_end)
                ploop_tracker_notify(io->plo, sec);


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