Patchwork [RFC,V3,3/9] quorum: Add quorum_open() and quorum_close().

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Submitter Benoit Canet
Date Aug. 14, 2012, 2:14 p.m.
Message ID <1344953651-16622-4-git-send-email-benoit@irqsave.net>
Download mbox | patch
Permalink /patch/177286/
State New
Headers show

Comments

Benoit Canet - Aug. 14, 2012, 2:14 p.m.
Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block/quorum.c |  113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
Eric Blake - Aug. 14, 2012, 2:45 p.m.
On 08/14/2012 08:14 AM, BenoƮt Canet wrote:
> Signed-off-by: Benoit Canet <benoit@irqsave.net>

Your commit message is sparse.  At least document the syntax expected
for opening a quorum file.

> ---
>  block/quorum.c |  113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 113 insertions(+)
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index bab6175..f228428 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -52,11 +52,124 @@ struct QuorumAIOCB {
>      int vote_ret;
>  };
>  
> +/* Valid quorum filenames look like
> + * quorum:n/m:path/to/image_1, ... ,path/to/image_m

such as copying this in the commit message.  Also, document your escape
handling; I had to read it from the code, but it looks like you set up
'\' to escape anything, so that '\:' and '\\' are the spellings for a
literal backslash or colon in a file name.

> + */
> +static int quorum_open(BlockDriverState *bs, const char *filename, int flags)
> +{
> +    BDRVQuorumState *s = bs->opaque;
> +    int escape, i, j, len, ret = 0;

escape only ever holds 0 or 1, so it should be a 'bool' instead.

> +    /* Get the filenames pointers */
> +    escape = 0;

s/0/false/

> +    s->filenames[0] = names;
> +    len = strlen(names);
> +    for (i = 0, j = 1; i < len && j < s->m; i++) {
> +        if (!escape && names[i] == ':') {
> +            names[i] = '\0';
> +            s->filenames[j] = names + i + 1;
> +            j += 1;

Isn't this usually written 'j++'?

> +        }
> +
> +        if (!escape && names[i] == '\\') {
> +            escape = 1;

s/1/true/

> +        } else {
> +            escape = 0;

s/0/false/

> +        }

Or even simplify the 'if' to a one-liner:

escape = !escape && names[i] == '\\';

Patch

diff --git a/block/quorum.c b/block/quorum.c
index bab6175..f228428 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -52,11 +52,124 @@  struct QuorumAIOCB {
     int vote_ret;
 };
 
+/* Valid quorum filenames look like
+ * quorum:n/m:path/to/image_1, ... ,path/to/image_m
+ */
+static int quorum_open(BlockDriverState *bs, const char *filename, int flags)
+{
+    BDRVQuorumState *s = bs->opaque;
+    int escape, i, j, len, ret = 0;
+    char *a, *b, *names;
+
+    /* Parse the quorum: prefix */
+    if (strncmp(filename, "quorum:", strlen("quorum:"))) {
+        return -EINVAL;
+    }
+
+    filename += strlen("quorum:");
+
+    /* Get n */
+    errno = 0;
+    s->n = strtoul(filename, &a, 10);
+    if (*a != '/' || errno) {
+        return -EINVAL;
+    }
+    a += 1;
+
+    /* Get m */
+    errno = 0;
+    s->m = strtoul(a, &b, 10);
+    if (*b != ':' || errno) {
+        return -EINVAL;
+    }
+    b += 1;
+
+    if (s->n < 1 || s->m < 2) {
+        return -EINVAL;
+    }
+
+    if (s->n > s->m) {
+        return -EINVAL;
+    }
+
+    s->bs = g_malloc0(sizeof(BlockDriverState *) * s->m);
+    /* Two allocations for all filenames: simpler to free */
+    s->filenames = g_malloc0(sizeof(char *) * s->m);
+    names = g_strdup(b);
+
+    /* Get the filenames pointers */
+    escape = 0;
+    s->filenames[0] = names;
+    len = strlen(names);
+    for (i = 0, j = 1; i < len && j < s->m; i++) {
+        if (!escape && names[i] == ':') {
+            names[i] = '\0';
+            s->filenames[j] = names + i + 1;
+            j += 1;
+        }
+
+        if (!escape && names[i] == '\\') {
+            escape = 1;
+        } else {
+            escape = 0;
+        }
+    }
+
+    if (j != s->m) {
+        ret = -EINVAL;
+        goto free_exit;
+    }
+
+    /* Open files */
+    for (i = 0; i < s->m; i++) {
+        s->bs[i] = bdrv_new("");
+        ret = bdrv_open(s->bs[i], s->filenames[i], flags, NULL);
+        if (ret < 0) {
+            goto error_exit;
+        }
+    }
+
+    goto exit;
+
+error_exit:
+    for (; i >= 0; i--) {
+        bdrv_delete(s->bs[i]);
+        s->bs[i] = NULL;
+    }
+free_exit:
+    g_free(s->filenames[0]);
+    g_free(s->filenames);
+    s->filenames = NULL;
+    g_free(s->bs);
+exit:
+    return ret;
+}
+
+static void quorum_close(BlockDriverState *bs)
+{
+    BDRVQuorumState *s = bs->opaque;
+    int i;
+
+    for (i = 0; i < s->m; i++) {
+        /* Ensure writes reach stable storage */
+        bdrv_flush(s->bs[i]);
+        bdrv_delete(s->bs[i]);
+    }
+
+    g_free(s->filenames[0]);
+    g_free(s->filenames);
+    s->filenames = NULL;
+    g_free(s->bs);
+}
+
 static BlockDriver bdrv_quorum = {
     .format_name        = "quorum",
     .protocol_name      = "quorum",
 
     .instance_size      = sizeof(BDRVQuorumState),
+
+    .bdrv_file_open     = quorum_open,
+    .bdrv_close         = quorum_close,
 };
 
 static void bdrv_quorum_init(void)