On 07/20/2012 09:15 PM, Josef Bacik wrote:
> SSD's do not gain anything by having metadata DUP turned on. The underlying
> file system that is a part of all SSD's could easily map duplicate metadat
If I understood correctly you are stating that because an SSD *might*
"eliminates the benefit of duplicating the metadata" mkfs.btrfs *must*
remove _silently_ this behaviour on all SSD ?
To me it seems too strong; or almost it should be documented in the man
page and/or issuing a warning during the format process.
> blocks into the same erase block which effectively eliminates the benefit of
> duplicating the metadata on disk. So detect if we are formatting a single
> SSD drive and if we are do not use DUP. Thanks,
>
> Signed-off-by: Josef Bacik <jba...@fusionio.com>
> ---
> V1->V2: use blkid to get the full disk in case we happen to be formatting a
> partition.
>
> Makefile | 2 +-
> mkfs.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 52 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 9694444..d827216 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -65,7 +65,7 @@ btrfsck: $(objects) btrfsck.o
> $(CC) $(CFLAGS) -o btrfsck btrfsck.o $(objects) $(LDFLAGS) $(LIBS)
>
> mkfs.btrfs: $(objects) mkfs.o
> - $(CC) $(CFLAGS) -o mkfs.btrfs $(objects) mkfs.o $(LDFLAGS) $(LIBS)
> + $(CC) $(CFLAGS) -o mkfs.btrfs $(objects) mkfs.o $(LDFLAGS) $(LIBS)
> -lblkid
>
> btrfs-debug-tree: $(objects) debug-tree.o
> $(CC) $(CFLAGS) -o btrfs-debug-tree $(objects) debug-tree.o $(LDFLAGS)
> $(LIBS)
> diff --git a/mkfs.c b/mkfs.c
> index dff5eb8..fc2b6ed 100644
> --- a/mkfs.c
> +++ b/mkfs.c
> @@ -37,6 +37,7 @@
> #include <linux/fs.h>
> #include <ctype.h>
> #include <attr/xattr.h>
> +#include <blkid/blkid.h>
> #include "kerncompat.h"
> #include "ctree.h"
> #include "disk-io.h"
> @@ -234,7 +235,7 @@ static int create_one_raid_group(struct
> btrfs_trans_handle *trans,
> static int create_raid_groups(struct btrfs_trans_handle *trans,
> struct btrfs_root *root, u64 data_profile,
> int data_profile_opt, u64 metadata_profile,
> - int metadata_profile_opt, int mixed)
> + int metadata_profile_opt, int mixed, int ssd)
> {
> u64 num_devices = btrfs_super_num_devices(&root->fs_info->super_copy);
> u64 allowed;
> @@ -246,7 +247,7 @@ static int create_raid_groups(struct btrfs_trans_handle
> *trans,
> */
> if (!metadata_profile_opt && !mixed) {
Please put something like
+ if(ssd)
+ printf("SSD detected: remove the metadata duplication;");
> metadata_profile = (num_devices > 1) ?
> - BTRFS_BLOCK_GROUP_RAID1 : BTRFS_BLOCK_GROUP_DUP;
> + BTRFS_BLOCK_GROUP_RAID1 : (ssd) ? 0:
> BTRFS_BLOCK_GROUP_DUP;
> }
> if (!data_profile_opt && !mixed) {
> data_profile = (num_devices > 1) ?
> @@ -1201,6 +1202,49 @@ static int zero_output_file(int out_fd, u64 size, u32
> sectorsize)
> return ret;
> }
>
> +static int is_ssd(const char *file)
> +{
> + char *devname;
> + blkid_probe probe;
> + char *dev;
> + char path[PATH_MAX];
> + dev_t disk;
> + int fd;
> + char rotational;
> +
> + probe = blkid_new_probe_from_filename(file);
> + if (!probe)
> + return 0;
> +
> + /*
> + * We want to use blkid_devno_to_wholedisk() but it's broken for some
> + * reason on F17 at least so we'll do this trickery
> + */
> + disk = blkid_probe_get_wholedisk_devno(probe);
> + devname = blkid_devno_to_devname(disk);
> +
> + dev = strrchr(devname, '/');
> + dev++;
> +
> + snprintf(path, PATH_MAX, "/sys/block/%s/queue/rotational", dev);
> +
> + free(devname);
> + blkid_free_probe(probe);
> +
> + fd = open(path, O_RDONLY);
> + if (fd < 0) {
> + return 0;
> + }
> +
> + if (read(fd, &rotational, sizeof(char)) < sizeof(char)) {
> + close(fd);
> + return 0;
> + }
> + close(fd);
> +
> + return !atoi((const char *)&rotational);
> +}
> +
> int main(int ac, char **av)
> {
> char *file;
> @@ -1227,6 +1271,7 @@ int main(int ac, char **av)
> int data_profile_opt = 0;
> int metadata_profile_opt = 0;
> int nodiscard = 0;
> + int ssd = 0;
>
> char *source_dir = NULL;
> int source_dir_set = 0;
> @@ -1352,6 +1397,9 @@ int main(int ac, char **av)
> exit(1);
> }
> }
> +
> + ssd = is_ssd(file);
> +
> if (mixed) {
> if (metadata_profile != data_profile) {
> fprintf(stderr, "With mixed block groups data and
> metadata "
> @@ -1438,7 +1486,7 @@ raid_groups:
> if (!source_dir_set) {
> ret = create_raid_groups(trans, root, data_profile,
> data_profile_opt, metadata_profile,
> - metadata_profile_opt, mixed);
> + metadata_profile_opt, mixed, ssd);
> BUG_ON(ret);
> }
>
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