Reintroduce IO accounting on zvols on Linux 3.19+

zfsonlinux/zfs@e20cd6f7a8922709b1aa2ecefd783390102d79e0 caused us to
lose IO accounting on zvols. When I originally wrote that last year, the
symbols we needed to maintain IO accounting were GPL exported, but
torvalds/linux@394ffa503bc40e32d7f54a9b817264e81ce131b4 provided
suitable symbols for restoring this functionality 4 months later.  We
can call them to restore the IO accounting on Linux 3.19 and later as
well as any older kernels where that patch is backported.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3741

diff --git a/config/kernel-generic_io_acct.m4 b/config/kernel-generic_io_acct.m4
new file mode 100644 (file)
index 0000000..25bfa38
--- /dev/null
+++ b/config/kernel-generic_io_acct.m4
@@ -0,0 +1,26 @@
+dnl #
+dnl # 3.19 API addition
+dnl #
+dnl # torvalds/linux@394ffa503bc40e32d7f54a9b817264e81ce131b4 allows us to
+dnl # increment iostat counters without generic_make_request().
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_GENERIC_IO_ACCT], [
+       AC_MSG_CHECKING([whether generic IO accounting symbols are avaliable])
+       ZFS_LINUX_TRY_COMPILE_SYMBOL([
+               #include <linux/bio.h>
+
+               void (*generic_start_io_acct_f)(int, unsigned long,
+                   struct hd_struct *) = &generic_start_io_acct;
+               void (*generic_end_io_acct_f)(int, struct hd_struct *,
+                   unsigned long) = &generic_end_io_acct;
+       ], [
+               generic_start_io_acct(0, 0, NULL);
+               generic_end_io_acct(0, NULL, 0);
+       ], [generic_start_io_acct], [block/bio.c], [
+               AC_MSG_RESULT(yes)
+               AC_DEFINE(HAVE_GENERIC_IO_ACCT, 1,
+                   [generic_start_io_acct()/generic_end_io_acct() avaliable])
+       ], [
+               AC_MSG_RESULT(no)
+       ])
+])

diff --git a/config/kernel.m4 b/config/kernel.m4
index 975e4226482cb7277feda6bcb5b802d357a5e804..e088c4da34ef28b530f03cb44a3dedb0251c537c 100644 (file)
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -94,6 +94,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
        ZFS_AC_KERNEL_KMAP_ATOMIC_ARGS
        ZFS_AC_KERNEL_FOLLOW_DOWN_ONE
        ZFS_AC_KERNEL_MAKE_REQUEST_FN
+       ZFS_AC_KERNEL_GENERIC_IO_ACCT
 
        AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
                KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"

diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
index c3c466bc2a25accca8525499cab860991d4a8695..162b315ea0c4c0038d5e98863946d7d5b48d304d 100644 (file)
--- a/include/linux/blkdev_compat.h
+++ b/include/linux/blkdev_compat.h
@@ -343,4 +343,9 @@ blk_queue_discard_granularity(struct request_queue *q, unsigned int dg)
  */
 #define        VDEV_HOLDER                     ((void *)0x2401de7)
 
+#ifndef HAVE_GENERIC_IO_ACCT
+#define        generic_start_io_acct(rw, slen, part)           ((void)0)
+#define        generic_end_io_acct(rw, part, start_jiffies)    ((void)0)
+#endif
+
 #endif /* _ZFS_BLKDEV_H */

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 492f8ff8793b05ad2aa6e67d48be6531a4bc8e10..7c1f024ca37e7db6bdb41758d2d71b1896a72459 100644 (file)
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -713,6 +713,10 @@ zvol_request(struct request_queue *q, struct bio *bio)
        fstrans_cookie_t cookie = spl_fstrans_mark();
        uint64_t offset = BIO_BI_SECTOR(bio);
        unsigned int sectors = bio_sectors(bio);
+       int rw = bio_data_dir(bio);
+#ifdef HAVE_GENERIC_IO_ACCT
+       unsigned long start = jiffies;
+#endif
        int error = 0;
 
        if (bio_has_data(bio) && offset + sectors >
@@ -723,25 +727,29 @@ zvol_request(struct request_queue *q, struct bio *bio)
                    (long long unsigned)offset,
                    (long unsigned)sectors);
                error = SET_ERROR(EIO);
-               goto out;
+               goto out1;
        }
 
-       if (bio_data_dir(bio) == WRITE) {
+       generic_start_io_acct(rw, sectors, &zv->zv_disk->part0);
+
+       if (rw == WRITE) {
                if (unlikely(zv->zv_flags & ZVOL_RDONLY)) {
                        error = SET_ERROR(EROFS);
-                       goto out;
+                       goto out2;
                }
 
                if (bio->bi_rw & VDEV_REQ_DISCARD) {
                        error = zvol_discard(bio);
-                       goto out;
+                       goto out2;
                }
 
                error = zvol_write(bio);
        } else
                error = zvol_read(bio);
 
-out:
+out2:
+       generic_end_io_acct(rw, &zv->zv_disk->part0, start);
+out1:
        bio_endio(bio, -error);
        spl_fstrans_unmark(cookie);
 #ifdef HAVE_MAKE_REQUEST_FN_RET_INT