[lvm-devel] [PATCH] update 'md_chunk_alignment' support to use stripe-width
Mike Snitzer
snitzer at redhat.com
Fri Jul 3 04:42:48 UTC 2009
Use the MD device's stripe-width, instead of chunk_size, to align the
data blocks of a Physical Volume that is placed directly upon an MD
device.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
lib/device/dev-md.c | 161 ++++++++++++++++++++++++++++++++++++++++--------
lib/device/device.h | 2
lib/metadata/metadata.c | 6 -
man/lvm.conf.5.in | 4 -
4 files changed, 143 insertions(+), 30 deletions(-)
diff --git a/lib/device/dev-md.c b/lib/device/dev-md.c
index 190bc88..7cb58e2 100644
--- a/lib/device/dev-md.c
+++ b/lib/device/dev-md.c
@@ -125,62 +125,175 @@ out:
return ret;
}
-/*
- * Retrieve chunk size from md device using sysfs.
- */
-unsigned long dev_md_chunk_size(const char *sysfs_dir, struct device *dev)
+static FILE *md_sysfs_fopen(const char *sysfs_dir, struct device *dev,
+ const char *attribute)
{
- char path[PATH_MAX+1], buffer[64];
+ char path[PATH_MAX+1];
FILE *fp;
struct stat info;
- unsigned long chunk_size_bytes = 0UL;
if (MAJOR(dev->dev) != md_major())
- return 0;
+ return NULL;
if (!sysfs_dir || !*sysfs_dir)
- return_0;
+ return NULL;
- if (dm_snprintf(path, PATH_MAX, "%s/dev/block/%d:%d/md/chunk_size",
- sysfs_dir, MAJOR(dev->dev), MINOR(dev->dev)) < 0) {
- log_error("dm_snprintf md chunk_size failed");
- return 0;
+ if (dm_snprintf(path, PATH_MAX, "%s/dev/block/%d:%d/md/%s",
+ sysfs_dir, MAJOR(dev->dev), MINOR(dev->dev), attribute) < 0) {
+ log_error("dm_snprintf md %s failed", attribute);
+ return NULL;
}
/* old sysfs structure */
if (stat(path, &info) &&
- dm_snprintf(path, PATH_MAX, "%s/block/md%d/md/chunk_size",
- sysfs_dir, MINOR(dev->dev)) < 0) {
- log_error("dm_snprintf old md chunk size failed");
- return 0;
+ dm_snprintf(path, PATH_MAX, "%s/block/md%d/md/%s",
+ sysfs_dir, MINOR(dev->dev), attribute) < 0) {
+ log_error("dm_snprintf old md %s failed", attribute);
+ return NULL;
}
if (!(fp = fopen(path, "r"))) {
log_sys_error("fopen", path);
- return 0;
+ return NULL;
}
+ return fp;
+}
+
+/*
+ * Retrieve chunk size from md device using sysfs.
+ */
+static unsigned long dev_md_chunk_size(const char *sysfs_dir,
+ struct device *dev)
+{
+ char buffer[64];
+ FILE *fp;
+ const char *attribute = "chunk_size";
+ unsigned long chunk_size_bytes = 0UL;
+
+ if (!(fp = md_sysfs_fopen(sysfs_dir, dev, attribute)))
+ return 0;
+
if (!fgets(buffer, sizeof(buffer), fp)) {
- log_sys_error("fgets", path);
+ log_sys_error("fgets", attribute);
goto out;
}
if (sscanf(buffer, "%lu", &chunk_size_bytes) != 1) {
- log_error("sysfs file %s not in expected format: %s", path,
- buffer);
+ log_error("%s sysfs attr %s not in expected format: %s",
+ dev_name(dev), attribute, buffer);
goto out;
}
- log_very_verbose("Device %s md chunk size is %lu bytes.",
+ log_very_verbose("Device %s chunk size is %lu bytes.",
dev_name(dev), chunk_size_bytes);
out:
if (fclose(fp))
- log_sys_error("fclose", path);
+ log_sys_error("fclose", attribute);
return chunk_size_bytes >> SECTOR_SHIFT;
}
+/*
+ * Retrieve level from md device using sysfs.
+ */
+static int dev_md_level(const char *sysfs_dir, struct device *dev)
+{
+ char buffer[64];
+ FILE *fp;
+ const char *attribute = "level";
+ int level = -1;
+
+ if (!(fp = md_sysfs_fopen(sysfs_dir, dev, attribute)))
+ return -1;
+
+ if (!fgets(buffer, sizeof(buffer), fp)) {
+ log_sys_error("fgets", attribute);
+ goto out;
+ }
+
+ if (sscanf(buffer, "raid%d", &level) != 1) {
+ log_error("%s sysfs attr %s not in expected format: %s",
+ dev_name(dev), attribute, buffer);
+ goto out;
+ }
+
+ log_very_verbose("Device %s raid level is %d.",
+ dev_name(dev), level);
+
+out:
+ if (fclose(fp))
+ log_sys_error("fclose", attribute);
+
+ return level;
+}
+
+/*
+ * Retrieve raid_disks from md device using sysfs.
+ */
+static int dev_md_raid_disks(const char *sysfs_dir, struct device *dev)
+{
+ char buffer[64];
+ FILE *fp;
+ const char *attribute = "raid_disks";
+ int raid_disks = 0;
+
+ if (!(fp = md_sysfs_fopen(sysfs_dir, dev, attribute)))
+ return 0;
+
+ if (!fgets(buffer, sizeof(buffer), fp)) {
+ log_sys_error("fgets", attribute);
+ goto out;
+ }
+
+ if (sscanf(buffer, "%d", &raid_disks) != 1) {
+ log_error("%s sysfs attr %s not in expected format: %s",
+ dev_name(dev), attribute, buffer);
+ goto out;
+ }
+
+ log_very_verbose("Device %s raid_disks is %d.",
+ dev_name(dev), raid_disks);
+
+out:
+ if (fclose(fp))
+ log_sys_error("fclose", attribute);
+
+ return raid_disks;
+}
+
+/*
+ * Calculate stripe width of md device using its sysfs files.
+ */
+unsigned long dev_md_stripe_width(const char *sysfs_dir, struct device *dev)
+{
+ unsigned long chunk_size_sectors = 0UL;
+ unsigned long stripe_width_sectors = 0UL;
+ int level, raid_disks, data_disks;
+
+ chunk_size_sectors = dev_md_chunk_size(sysfs_dir, dev);
+ if (!chunk_size_sectors)
+ return 0;
+
+ level = dev_md_level(sysfs_dir, dev);
+ if (level < 0)
+ return 0;
+
+ raid_disks = dev_md_raid_disks(sysfs_dir, dev);
+ if (!raid_disks)
+ return 0;
+
+ data_disks = raid_disks - (level == 0 ? 0 : (level <= 5 ? 1 : 2));
+ stripe_width_sectors = chunk_size_sectors * data_disks;
+
+ log_very_verbose("Device %s stripe-width is %lu bytes.",
+ dev_name(dev),
+ stripe_width_sectors << SECTOR_SHIFT);
+
+ return stripe_width_sectors;
+}
+
#else
int dev_is_md(struct device *dev __attribute((unused)),
@@ -189,8 +302,8 @@ int dev_is_md(struct device *dev __attribute((unused)),
return 0;
}
-unsigned long dev_md_chunk_size(const char *sysfs_dir __attribute((unused)),
- struct device *dev __attribute((unused)))
+unsigned long dev_md_stripe_width(const char *sysfs_dir __attribute((unused)),
+ struct device *dev __attribute((unused)))
{
return 0UL;
}
diff --git a/lib/device/device.h b/lib/device/device.h
index 94f17b4..b016823 100644
--- a/lib/device/device.h
+++ b/lib/device/device.h
@@ -96,7 +96,7 @@ const char *dev_name_confirmed(struct device *dev, int quiet);
/* Does device contain md superblock? If so, where? */
int dev_is_md(struct device *dev, uint64_t *sb);
int dev_is_swap(struct device *dev, uint64_t *signature);
-unsigned long dev_md_chunk_size(const char *sysfs_dir, struct device *dev);
+unsigned long dev_md_stripe_width(const char *sysfs_dir, struct device *dev);
int is_partitioned_dev(struct device *dev);
diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index dc7e759..fda07be 100644
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -81,13 +81,13 @@ unsigned long set_pe_align(struct physical_volume *pv, unsigned long data_alignm
goto out;
/*
- * Align to chunk size of underlying md device if present
+ * Align to stripe-width of underlying md device if present
*/
if (find_config_tree_bool(pv->fmt->cmd, "devices/md_chunk_alignment",
DEFAULT_MD_CHUNK_ALIGNMENT))
pv->pe_align = MAX(pv->pe_align,
- dev_md_chunk_size(pv->fmt->cmd->sysfs_dir,
- pv->dev));
+ dev_md_stripe_width(pv->fmt->cmd->sysfs_dir,
+ pv->dev));
log_very_verbose("%s: Setting PE alignment to %lu sectors.",
dev_name(pv->dev), pv->pe_align);
diff --git a/man/lvm.conf.5.in b/man/lvm.conf.5.in
index 68024b6..0e3a949 100644
--- a/man/lvm.conf.5.in
+++ b/man/lvm.conf.5.in
@@ -134,8 +134,8 @@ superblocks. This doesn't always work satisfactorily e.g. if a device
has been reused without wiping the md superblocks first.
.IP
\fBmd_chunk_alignment\fP \(em If set to 1, and a Physical Volume is placed
-directly upon an md device, LVM2 will align its data blocks with the the
-chunk_size exposed in sysfs.
+directly upon an md device, LVM2 will align its data blocks with the
+md device's stripe-width.
.IP
\fBdata_alignment\fP \(em Default alignment (in KB) of start of data area
when creating a new Physical Volume using the \fBlvm2\fP format.
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