From ea0e0a4820d0dfa1227bd8351d89e9d55b25da44 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 17 Mar 2015 12:59:01 +0100

Subject: [PATCH 12/16] raw-posix: Fail gracefully if no working alignment is

 found

Message-id: <1424365599-9801-3-git-send-email-stefanha@redhat.com>

Patchwork-id: 63913

O-Subject: [RHEL-7.1 qemu-kvm PATCH 2/2] raw-posix: Fail gracefully if no working alignment is found

Bugzilla: 1184363

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

From: Kevin Wolf <kwolf@redhat.com>

If qemu couldn't find out what O_DIRECT alignment to use with a given

file, it would run into assert(bdrv_opt_mem_align(bs) != 0); in block.c

and confuse users. This adds a more descriptive error message for such

cases.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit df26a35025427f34c1d4e5a8e51152371a5e231e)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

 block/raw-posix.c | 35 +++++++++++++++++++++++++++--------

 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c

index 6a50856..af526ca 100644

--- a/block/raw-posix.c

+++ b/block/raw-posix.c

@@ -213,7 +213,7 @@ static int raw_normalize_devicepath(const char **filename)

 }

 #endif

-static void raw_probe_alignment(BlockDriverState *bs)

+static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)

 {

     BDRVRawState *s = bs->opaque;

     char *buf;

@@ -232,24 +232,24 @@ static void raw_probe_alignment(BlockDriverState *bs)

     s->buf_align = 0;

 #ifdef BLKSSZGET

-    if (ioctl(s->fd, BLKSSZGET, &sector_size) >= 0) {

+    if (ioctl(fd, BLKSSZGET, &sector_size) >= 0) {

         bs->request_alignment = sector_size;

     }

 #endif

 #ifdef DKIOCGETBLOCKSIZE

-    if (ioctl(s->fd, DKIOCGETBLOCKSIZE, &sector_size) >= 0) {

+    if (ioctl(fd, DKIOCGETBLOCKSIZE, &sector_size) >= 0) {

         bs->request_alignment = sector_size;

     }

 #endif

 #ifdef DIOCGSECTORSIZE

-    if (ioctl(s->fd, DIOCGSECTORSIZE, &sector_size) >= 0) {

+    if (ioctl(fd, DIOCGSECTORSIZE, &sector_size) >= 0) {

         bs->request_alignment = sector_size;

     }

 #endif

 #ifdef CONFIG_XFS

     if (s->is_xfs) {

         struct dioattr da;

-        if (xfsctl(NULL, s->fd, XFS_IOC_DIOINFO, &da) >= 0) {

+        if (xfsctl(NULL, fd, XFS_IOC_DIOINFO, &da) >= 0) {

             bs->request_alignment = da.d_miniosz;

             /* The kernel returns wrong information for d_mem */

             /* s->buf_align = da.d_mem; */

@@ -262,7 +262,7 @@ static void raw_probe_alignment(BlockDriverState *bs)

         size_t align;

         buf = qemu_memalign(MAX_BLOCKSIZE, 2 * MAX_BLOCKSIZE);

         for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {

-            if (pread(s->fd, buf + align, MAX_BLOCKSIZE, 0) >= 0) {

+            if (pread(fd, buf + align, MAX_BLOCKSIZE, 0) >= 0) {

                 s->buf_align = align;

                 break;

             }

@@ -274,13 +274,18 @@ static void raw_probe_alignment(BlockDriverState *bs)

         size_t align;

         buf = qemu_memalign(s->buf_align, MAX_BLOCKSIZE);

         for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {

-            if (pread(s->fd, buf, align, 0) >= 0) {

+            if (pread(fd, buf, align, 0) >= 0) {

                 bs->request_alignment = align;

                 break;

             }

         }

         qemu_vfree(buf);

     }

+

+    if (!s->buf_align || !bs->request_alignment) {

+        error_setg(errp, "Could not find working O_DIRECT alignment. "

+                         "Try cache.direct=off.");

+    }

 }

 static void raw_parse_flags(int bdrv_flags, int *open_flags)

@@ -459,6 +464,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,

     BDRVRawState *s;

     BDRVRawReopenState *raw_s;

     int ret = 0;

+    Error *local_err = NULL;

     assert(state != NULL);

     assert(state->bs != NULL);

@@ -531,6 +537,19 @@ static int raw_reopen_prepare(BDRVReopenState *state,

             ret = -1;

         }

     }

+

+    /* Fail already reopen_prepare() if we can't get a working O_DIRECT

+     * alignment with the new fd. */

+    if (raw_s->fd != -1) {

+        raw_probe_alignment(state->bs, raw_s->fd, &local_err);

+        if (local_err) {

+            qemu_close(raw_s->fd);

+            raw_s->fd = -1;

+            error_propagate(errp, local_err);

+            ret = -EINVAL;

+        }

+    }

+

     return ret;

 }

@@ -573,7 +592,7 @@ static int raw_refresh_limits(BlockDriverState *bs)

 {

     BDRVRawState *s = bs->opaque;

-    raw_probe_alignment(bs);

+    raw_probe_alignment(bs, s->fd, errp);

     bs->bl.opt_mem_alignment = s->buf_align;

     return 0;

-- 

1.8.3.1