| Message ID | 20181011185103.23146-2-kreijack@libero.it (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/9] btrfs: Add support for reading a filesystem with a RAID 5 or RAID 6 profile. | expand |
On Thu, Oct 11, 2018 at 08:50:55PM +0200, Goffredo Baroncelli wrote: > From: Goffredo Baroncelli <kreijack@inwind.it> > > Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it> > Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> One nit pick below... Otherwise you can add Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> > --- > grub-core/fs/btrfs.c | 73 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 73 insertions(+) > > diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c > index be195448d..933a57d3b 100644 > --- a/grub-core/fs/btrfs.c > +++ b/grub-core/fs/btrfs.c > @@ -119,6 +119,8 @@ struct grub_btrfs_chunk_item > #define GRUB_BTRFS_CHUNK_TYPE_RAID1 0x10 > #define GRUB_BTRFS_CHUNK_TYPE_DUPLICATED 0x20 > #define GRUB_BTRFS_CHUNK_TYPE_RAID10 0x40 > +#define GRUB_BTRFS_CHUNK_TYPE_RAID5 0x80 > +#define GRUB_BTRFS_CHUNK_TYPE_RAID6 0x100 > grub_uint8_t dummy2[0xc]; > grub_uint16_t nstripes; > grub_uint16_t nsubstripes; > @@ -764,6 +766,77 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, > stripe_offset = low + chunk_stripe_length > * high; > csize = chunk_stripe_length - low; > + break; > + } > + case GRUB_BTRFS_CHUNK_TYPE_RAID5: > + case GRUB_BTRFS_CHUNK_TYPE_RAID6: > + { > + grub_uint64_t nparities, stripe_nr, high, low; > + > + redundancy = 1; /* no redundancy for now */ > + > + if (grub_le_to_cpu64 (chunk->type) & GRUB_BTRFS_CHUNK_TYPE_RAID5) > + { > + grub_dprintf ("btrfs", "RAID5\n"); > + nparities = 1; > + } > + else > + { > + grub_dprintf ("btrfs", "RAID6\n"); > + nparities = 2; > + } > + > + /* > + * RAID 6 layout consists of several stripes spread over > + * the disks, e.g.: > + * > + * Disk_0 Disk_1 Disk_2 Disk_3 > + * A0 B0 P0 Q0 > + * Q1 A1 B1 P1 > + * P2 Q2 A2 B2 > + * > + * Note: placement of the parities depend on row number. > + * > + * Pay attention that the btrfs terminology may differ from > + * terminology used in other RAID implementations, e.g. LVM, > + * dm or md. The main difference is that btrfs calls contiguous > + * block of data on a given disk, e.g. A0, stripe instead of chunk. > + * > + * The variables listed below have following meaning: > + * - stripe_nr is the stripe number excluding the parities > + * (A0 = 0, B0 = 1, A1 = 2, B1 = 3, etc.), > + * - high is the row number (0 for A0...Q0, 1 for Q1...P1, etc.), > + * - stripen is the disk number in a row (0 for A0, Q1, P2, > + * 1 for B0, A1, Q2, etc.), > + * - off is the logical address to read, > + * - chunk_stripe_length is the size of a stripe (typically 64 KiB), > + * - nstripes is the number of disks in a row, > + * - low is the offset of the data inside a stripe, > + * - stripe_offset is the data offset in an array, > + * - csize is the "potential" data to read; it will be reduced > + * to size if the latter is smaller, > + * - nparities is the number of parities (1 for RAID 5, 2 for > + * RAID 6); used only in RAID 5/6 code. > + */ > + stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low); > + > + /* > + * stripen is computed without the parities > + * (0 for A0, A1, A2, 1 for B0, B1, B2, etc.). > + */ > + high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen); > + > + /* > + * The stripes are spread over the disks. Every each row their > + * positions are shifted by 1 place. So, the real disks number > + * change. Hence, we have to take current row number modulo > + * nstripes into account (0 for A0, 1 for A1, 2 for A2, etc.). s/current row number modulo nstripes into account/into account current row number modulo nstripes/ Daniel
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index be195448d..933a57d3b 100644 --- a/grub-core/fs/btrfs.c +++ b/grub-core/fs/btrfs.c @@ -119,6 +119,8 @@ struct grub_btrfs_chunk_item #define GRUB_BTRFS_CHUNK_TYPE_RAID1 0x10 #define GRUB_BTRFS_CHUNK_TYPE_DUPLICATED 0x20 #define GRUB_BTRFS_CHUNK_TYPE_RAID10 0x40 +#define GRUB_BTRFS_CHUNK_TYPE_RAID5 0x80 +#define GRUB_BTRFS_CHUNK_TYPE_RAID6 0x100 grub_uint8_t dummy2[0xc]; grub_uint16_t nstripes; grub_uint16_t nsubstripes; @@ -764,6 +766,77 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, stripe_offset = low + chunk_stripe_length * high; csize = chunk_stripe_length - low; + break; + } + case GRUB_BTRFS_CHUNK_TYPE_RAID5: + case GRUB_BTRFS_CHUNK_TYPE_RAID6: + { + grub_uint64_t nparities, stripe_nr, high, low; + + redundancy = 1; /* no redundancy for now */ + + if (grub_le_to_cpu64 (chunk->type) & GRUB_BTRFS_CHUNK_TYPE_RAID5) + { + grub_dprintf ("btrfs", "RAID5\n"); + nparities = 1; + } + else + { + grub_dprintf ("btrfs", "RAID6\n"); + nparities = 2; + } + + /* + * RAID 6 layout consists of several stripes spread over + * the disks, e.g.: + * + * Disk_0 Disk_1 Disk_2 Disk_3 + * A0 B0 P0 Q0 + * Q1 A1 B1 P1 + * P2 Q2 A2 B2 + * + * Note: placement of the parities depend on row number. + * + * Pay attention that the btrfs terminology may differ from + * terminology used in other RAID implementations, e.g. LVM, + * dm or md. The main difference is that btrfs calls contiguous + * block of data on a given disk, e.g. A0, stripe instead of chunk. + * + * The variables listed below have following meaning: + * - stripe_nr is the stripe number excluding the parities + * (A0 = 0, B0 = 1, A1 = 2, B1 = 3, etc.), + * - high is the row number (0 for A0...Q0, 1 for Q1...P1, etc.), + * - stripen is the disk number in a row (0 for A0, Q1, P2, + * 1 for B0, A1, Q2, etc.), + * - off is the logical address to read, + * - chunk_stripe_length is the size of a stripe (typically 64 KiB), + * - nstripes is the number of disks in a row, + * - low is the offset of the data inside a stripe, + * - stripe_offset is the data offset in an array, + * - csize is the "potential" data to read; it will be reduced + * to size if the latter is smaller, + * - nparities is the number of parities (1 for RAID 5, 2 for + * RAID 6); used only in RAID 5/6 code. + */ + stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low); + + /* + * stripen is computed without the parities + * (0 for A0, A1, A2, 1 for B0, B1, B2, etc.). + */ + high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen); + + /* + * The stripes are spread over the disks. Every each row their + * positions are shifted by 1 place. So, the real disks number + * change. Hence, we have to take current row number modulo + * nstripes into account (0 for A0, 1 for A1, 2 for A2, etc.). + */ + grub_divmod64 (high + stripen, nstripes, &stripen); + + stripe_offset = low + chunk_stripe_length * high; + csize = chunk_stripe_length - low; + break; } default: