diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2013-03-01 22:45:49 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2013-03-01 22:45:49 +0000 |
| commit | a26062416ef8add48f16fbadded2b5f6fb84d024 (patch) | |
| tree | 4f960c51bd22d99e55a1f56cf28f86f018de01a3 | |
| parent | 02cde50b7ea74557d32ff778c73809322445ccd2 (diff) | |
dm ioctl: allow message to return data
This patch introduces enhanced message support that allows the
device-mapper core to recognise messages that are common to all devices,
and for messages to return data to userspace.
Core messages are processed by the function "message_for_md". If the
device mapper doesn't support the message, it is passed to the target
driver.
If the message returns data, the kernel sets the flag
DM_MESSAGE_OUT_FLAG.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | drivers/md/dm-ioctl.c | 36 | ||||
| -rw-r--r-- | include/uapi/linux/dm-ioctl.h | 5 |
2 files changed, 40 insertions, 1 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 7eb0682d574f..aa04f0224642 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1414,6 +1414,22 @@ static int table_status(struct dm_ioctl *param, size_t param_size) return 0; } +static bool buffer_test_overflow(char *result, unsigned maxlen) +{ + return !maxlen || strlen(result) + 1 >= maxlen; +} + +/* + * Process device-mapper dependent messages. + * Returns a number <= 1 if message was processed by device mapper. + * Returns 2 if message should be delivered to the target. + */ +static int message_for_md(struct mapped_device *md, unsigned argc, char **argv, + char *result, unsigned maxlen) +{ + return 2; +} + /* * Pass a message to the target that's at the supplied device offset. */ @@ -1425,6 +1441,8 @@ static int target_message(struct dm_ioctl *param, size_t param_size) struct dm_table *table; struct dm_target *ti; struct dm_target_msg *tmsg = (void *) param + param->data_start; + size_t maxlen; + char *result = get_result_buffer(param, param_size, &maxlen); md = find_device(param); if (!md) @@ -1448,6 +1466,10 @@ static int target_message(struct dm_ioctl *param, size_t param_size) goto out_argv; } + r = message_for_md(md, argc, argv, result, maxlen); + if (r <= 1) + goto out_argv; + table = dm_get_live_table(md); if (!table) goto out_argv; @@ -1473,7 +1495,18 @@ static int target_message(struct dm_ioctl *param, size_t param_size) out_argv: kfree(argv); out: - param->data_size = 0; + if (r >= 0) + __dev_status(md, param); + + if (r == 1) { + param->flags |= DM_DATA_OUT_FLAG; + if (buffer_test_overflow(result, maxlen)) + param->flags |= DM_BUFFER_FULL_FLAG; + else + param->data_size = param->data_start + strlen(result) + 1; + r = 0; + } + dm_put(md); return r; } @@ -1653,6 +1686,7 @@ static int validate_params(uint cmd, struct dm_ioctl *param) param->flags &= ~DM_BUFFER_FULL_FLAG; param->flags &= ~DM_UEVENT_GENERATED_FLAG; param->flags &= ~DM_SECURE_DATA_FLAG; + param->flags &= ~DM_DATA_OUT_FLAG; /* Ignores parameters */ if (cmd == DM_REMOVE_ALL_CMD || diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index b8a6bddf0727..7e75b6fd8d45 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -336,4 +336,9 @@ enum { */ #define DM_SECURE_DATA_FLAG (1 << 15) /* In */ +/* + * If set, a message generated output data. + */ +#define DM_DATA_OUT_FLAG (1 << 16) /* Out */ + #endif /* _LINUX_DM_IOCTL_H */ |