* [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command
@ 2019-08-20 16:46 Denis Plotnikov
2019-08-20 17:24 ` Eric Blake
0 siblings, 1 reply; 4+ messages in thread
From: Denis Plotnikov @ 2019-08-20 16:46 UTC (permalink / raw)
To: qemu-devel; +Cc: kwolf, qemu-block, mreitz
The patch allows to provide a pattern file for write
command. There was no similar ability before.
Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
v10:
* fix overflow [Max]
* remove casting to bool [Max, Eric]
* fix wording [Max]
v9:
* replace flag cast to int with bool [Eric]
* fix the error message [Eric]
* use qemu_io_free instead of qemu_vfree [Eric]
* add function description [Eric]
v8: fix according to Max's comments
* get rid of unnecessary buffer for the pattern
* buffer allocation just in bytes
* take into account the missalign offset
* don't copy file name
* changed char* to const char* in input params
v7:
* fix variable naming
* make code more readable
* extend help for write command
v6:
* the pattern file is read once to reduce io
v5:
* file name initiated with null to make compilers happy
v4:
* missing signed-off clause added
v3:
* missing file closing added
* exclusive flags processing changed
* buffer void* converted to char* to fix pointer arithmetics
* file reading error processing added
---
qemu-io-cmds.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 93 insertions(+), 6 deletions(-)
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 09750a23ce..f411811d95 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -351,6 +351,79 @@ static void qemu_io_free(void *p)
qemu_vfree(p);
}
+/*
+ * qemu_io_alloc_from_file()
+ *
+ * Allocates the buffer and populates it with the content of the given file
+ * up to @len bytes. If the file length is less than @len, then the buffer
+ * is populated with the file content cyclically.
+ *
+ * @blk - the block backend where the buffer content is going to be written to
+ * @len - the buffer length
+ * @file_name - the file to read the content from
+ *
+ * Returns: the buffer pointer on success
+ * NULL on error
+ */
+static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
+ const char *file_name)
+{
+ char *buf, *buf_origin;
+ FILE *f = fopen(file_name, "r");
+ int pattern_len;
+
+ if (!f) {
+ perror(file_name);
+ return NULL;
+ }
+
+ if (qemuio_misalign) {
+ len += MISALIGN_OFFSET;
+ }
+
+ buf_origin = buf = blk_blockalign(blk, len);
+
+ if (qemuio_misalign) {
+ buf_origin += MISALIGN_OFFSET;
+ buf += MISALIGN_OFFSET;
+ len -= MISALIGN_OFFSET;
+ }
+
+ pattern_len = fread(buf_origin, 1, len, f);
+
+ if (ferror(f)) {
+ perror(file_name);
+ goto error;
+ }
+
+ if (pattern_len == 0) {
+ fprintf(stderr, "%s: file is empty\n", file_name);
+ goto error;
+ }
+
+ fclose(f);
+
+ if (len > pattern_len) {
+ len -= pattern_len;
+ buf += pattern_len;
+
+ while (len > 0) {
+ size_t len_to_copy = MIN(pattern_len, len);
+
+ memcpy(buf, buf_origin, len_to_copy);
+
+ len -= len_to_copy;
+ buf += len_to_copy;
+ }
+ }
+
+ return buf_origin;
+
+error:
+ qemu_io_free(buf_origin);
+ return NULL;
+}
+
static void dump_buffer(const void *buffer, int64_t offset, int64_t len)
{
uint64_t i;
@@ -949,6 +1022,7 @@ static void write_help(void)
" -n, -- with -z, don't allow slow fallback\n"
" -p, -- ignored for backwards compatibility\n"
" -P, -- use different pattern to fill file\n"
+" -s, -- use a pattern file to fill the write buffer\n"
" -C, -- report statistics in a machine parsable format\n"
" -q, -- quiet mode, do not show I/O statistics\n"
" -u, -- with -z, allow unmapping\n"
@@ -965,7 +1039,7 @@ static const cmdinfo_t write_cmd = {
.perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
- .args = "[-bcCfnquz] [-P pattern] off len",
+ .args = "[-bcCfnquz] [-P pattern | -s source_file] off len",
.oneline = "writes a number of bytes at a specified offset",
.help = write_help,
};
@@ -974,7 +1048,7 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
{
struct timeval t1, t2;
bool Cflag = false, qflag = false, bflag = false;
- bool Pflag = false, zflag = false, cflag = false;
+ bool Pflag = false, zflag = false, cflag = false, sflag = false;
int flags = 0;
int c, cnt, ret;
char *buf = NULL;
@@ -983,8 +1057,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
/* Some compilers get confused and warn if this is not initialized. */
int64_t total = 0;
int pattern = 0xcd;
+ const char *file_name = NULL;
- while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
+ while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
switch (c) {
case 'b':
bflag = true;
@@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
case 'z':
zflag = true;
break;
+ case 's':
+ sflag = true;
+ file_name = optarg;
+ break;
default:
qemuio_command_usage(&write_cmd);
return -EINVAL;
@@ -1051,8 +1130,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
return -EINVAL;
}
- if (zflag && Pflag) {
- printf("-z and -P cannot be specified at the same time\n");
+ if (zflag + Pflag + sflag > 1) {
+ printf("Only one of -z, -P, and -s "
+ "can be specified at the same time\n");
return -EINVAL;
}
@@ -1088,7 +1168,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
}
if (!zflag) {
- buf = qemu_io_alloc(blk, count, pattern);
+ if (sflag) {
+ buf = qemu_io_alloc_from_file(blk, count, file_name);
+ if (!buf) {
+ return -EINVAL;
+ }
+ } else {
+ buf = qemu_io_alloc(blk, count, pattern);
+ }
}
gettimeofday(&t1, NULL);
--
2.17.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command
2019-08-20 16:46 [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command Denis Plotnikov
@ 2019-08-20 17:24 ` Eric Blake
2019-08-20 19:16 ` Max Reitz
2019-08-20 19:19 ` John Snow
0 siblings, 2 replies; 4+ messages in thread
From: Eric Blake @ 2019-08-20 17:24 UTC (permalink / raw)
To: Denis Plotnikov, qemu-devel; +Cc: kwolf, qemu-block, mreitz
[-- Attachment #1.1: Type: text/plain, Size: 2553 bytes --]
On 8/20/19 11:46 AM, Denis Plotnikov wrote:
> The patch allows to provide a pattern file for write
> command. There was no similar ability before.
>
> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
> ---
> @@ -983,8 +1057,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
> /* Some compilers get confused and warn if this is not initialized. */
> int64_t total = 0;
> int pattern = 0xcd;
> + const char *file_name = NULL;
>
> - while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
> + while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
This one looks odd (I would have preserved ordering by sticking s:
between q and u). But a maintainer could fix that.
> switch (c) {
> case 'b':
> bflag = true;
> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
> case 'z':
> zflag = true;
> break;
> + case 's':
> + sflag = true;
> + file_name = optarg;
> + break;
Likewise, sorting the cases in the same order as the getopt() listing
helps in finding code during later edits.
> @@ -1088,7 +1168,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
> }
>
> if (!zflag) {
> - buf = qemu_io_alloc(blk, count, pattern);
> + if (sflag) {
> + buf = qemu_io_alloc_from_file(blk, count, file_name);
> + if (!buf) {
> + return -EINVAL;
> + }
> + } else {
> + buf = qemu_io_alloc(blk, count, pattern);
> + }
Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
returning NULL on huge allocation requests that can't be met. (Then
again, we have an early exit on any length > 2G, and 2G allocations tend
to succeed on modern development machines). Perhaps it would be nice to
teach qemu-io to use blk_try_blockalign for more graceful handling even
on 32-bit platforms, but that's not the problem of your patch.
Option ordering is minor enough that I'm fine giving:
Reviewed-by: Eric Blake <eblake@redhat.com>
Now, to figure out which maintainer should take it. Perhaps you want to
add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
doesn't regress, and b) makes it reasonable to take in through the
iotest tree.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command
2019-08-20 17:24 ` Eric Blake
@ 2019-08-20 19:16 ` Max Reitz
2019-08-20 19:19 ` John Snow
1 sibling, 0 replies; 4+ messages in thread
From: Max Reitz @ 2019-08-20 19:16 UTC (permalink / raw)
To: Eric Blake, Denis Plotnikov, qemu-devel; +Cc: kwolf, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 4209 bytes --]
On 20.08.19 19:24, Eric Blake wrote:
> On 8/20/19 11:46 AM, Denis Plotnikov wrote:
>> The patch allows to provide a pattern file for write
>> command. There was no similar ability before.
>>
>> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
>> ---
>
>> @@ -983,8 +1057,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> /* Some compilers get confused and warn if this is not initialized. */
>> int64_t total = 0;
>> int pattern = 0xcd;
>> + const char *file_name = NULL;
>>
>> - while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
>> + while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
>
> This one looks odd (I would have preserved ordering by sticking s:
> between q and u). But a maintainer could fix that.
>
>> switch (c) {
>> case 'b':
>> bflag = true;
>> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> case 'z':
>> zflag = true;
>> break;
>> + case 's':
>> + sflag = true;
>> + file_name = optarg;
>> + break;
>
> Likewise, sorting the cases in the same order as the getopt() listing
> helps in finding code during later edits.
But it is in order of the getopt() listing. ;-)
>> @@ -1088,7 +1168,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> }
>>
>> if (!zflag) {
>> - buf = qemu_io_alloc(blk, count, pattern);
>> + if (sflag) {
>> + buf = qemu_io_alloc_from_file(blk, count, file_name);
>> + if (!buf) {
>> + return -EINVAL;
>> + }
>> + } else {
>> + buf = qemu_io_alloc(blk, count, pattern);
>> + }
>
> Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
> returning NULL on huge allocation requests that can't be met. (Then
> again, we have an early exit on any length > 2G, and 2G allocations tend
> to succeed on modern development machines). Perhaps it would be nice to
> teach qemu-io to use blk_try_blockalign for more graceful handling even
> on 32-bit platforms, but that's not the problem of your patch.
Then again, this is qemu-io. Printing an error instead of just aborting
doesn’t really help anyone.
Also, the code would be wrong without an early exit on a length >
INT_MAX. (Because pattern_len is an int, so the result of fread() might
overflow otherwise, which would be bad.)
(I just noticed that fread() might do a short read, but let’s just
ignore this at this point.)
> Option ordering is minor enough that I'm fine giving:
>
> Reviewed-by: Eric Blake <eblake@redhat.com>
>
> Now, to figure out which maintainer should take it. Perhaps you want to
> add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
> doesn't regress, and b) makes it reasonable to take in through the
> iotest tree.
Adding a test does not seem to bad of an idea, but I don’t see how that
would clarify things. Both qemu-io and the iotests are part of the
block layer core:
$ scripts/get_maintainer.pl -f qemu-io-cmds.c
Kevin Wolf <kwolf@redhat.com> (supporter:Block layer core)
Max Reitz <mreitz@redhat.com> (supporter:Block layer core)
qemu-block@nongnu.org (open list:Block layer core)
qemu-devel@nongnu.org (open list:All patches CC here)
$ scripts/get_maintainer.pl -f tests/qemu-iotests
Kevin Wolf <kwolf@redhat.com> (supporter:Block layer core)
Max Reitz <mreitz@redhat.com> (supporter:Block layer core)
qemu-block@nongnu.org (open list:Block layer core)
qemu-devel@nongnu.org (open list:All patches CC here)
So we only need to figure out whether it should be Kevin or me to take
it; but Kevin is on PTO, so that decision is simple. :-)
Therefor, I’ve changed the optstring (and switch case) order to be
alphabetical, and applied the patch to my block branch:
https://git.xanclic.moe/XanClic/qemu/commits/branch/block
Thanks for the patch and the review,
Max
(I wouldn’t mind an iotest, but well. qemu-io itself is a testing
utility, so I don’t deem it important to test it.)
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command
2019-08-20 17:24 ` Eric Blake
2019-08-20 19:16 ` Max Reitz
@ 2019-08-20 19:19 ` John Snow
1 sibling, 0 replies; 4+ messages in thread
From: John Snow @ 2019-08-20 19:19 UTC (permalink / raw)
To: Eric Blake, Denis Plotnikov, qemu-devel; +Cc: kwolf, qemu-block, mreitz
On 8/20/19 1:24 PM, Eric Blake wrote:
> On 8/20/19 11:46 AM, Denis Plotnikov wrote:
>> The patch allows to provide a pattern file for write
>> command. There was no similar ability before.
>>
>> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
>> ---
>
>> @@ -983,8 +1057,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> /* Some compilers get confused and warn if this is not initialized. */
>> int64_t total = 0;
>> int pattern = 0xcd;
>> + const char *file_name = NULL;
>>
>> - while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
>> + while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
>
> This one looks odd (I would have preserved ordering by sticking s:
> between q and u). But a maintainer could fix that.
>
>> switch (c) {
>> case 'b':
>> bflag = true;
>> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> case 'z':
>> zflag = true;
>> break;
>> + case 's':
>> + sflag = true;
>> + file_name = optarg;
>> + break;
>
> Likewise, sorting the cases in the same order as the getopt() listing
> helps in finding code during later edits.
>
>> @@ -1088,7 +1168,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>> }
>>
>> if (!zflag) {
>> - buf = qemu_io_alloc(blk, count, pattern);
>> + if (sflag) {
>> + buf = qemu_io_alloc_from_file(blk, count, file_name);
>> + if (!buf) {
>> + return -EINVAL;
>> + }
>> + } else {
>> + buf = qemu_io_alloc(blk, count, pattern);
>> + }
>
> Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
> returning NULL on huge allocation requests that can't be met. (Then
> again, we have an early exit on any length > 2G, and 2G allocations tend
> to succeed on modern development machines). Perhaps it would be nice to
> teach qemu-io to use blk_try_blockalign for more graceful handling even
> on 32-bit platforms, but that's not the problem of your patch.
>
> Option ordering is minor enough that I'm fine giving:
>
> Reviewed-by: Eric Blake <eblake@redhat.com>
>
> Now, to figure out which maintainer should take it. Perhaps you want to
> add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
> doesn't regress, and b) makes it reasonable to take in through the
> iotest tree.
>
Yes, this is a good idea. I'm sure over time we'll pick up uses of
pattern writing that will strengthen the the regression testing of the
feature, but for now a simple test case will help ensure it.
(It'll also help "document" how to use the feature for other test writers.)
Thanks!
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-08-20 16:46 [Qemu-devel] [PATCH v10] qemu-io: add pattern file for write command Denis Plotnikov
2019-08-20 17:24 ` Eric Blake
2019-08-20 19:16 ` Max Reitz
2019-08-20 19:19 ` John Snow
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