| Message ID | 20180927183504.18078-2-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, Sep 27, 2018 at 08:34:56PM +0200, Goffredo Baroncelli wrote: > From: Goffredo Baroncelli <kreijack@inwind.it> > > Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it> Code LGTM. Though comment begs improvement. I will send you updated comment for approval shortly. Daniel
On Tue, Oct 09, 2018 at 07:51:01PM +0200, Daniel Kiper wrote: > On Thu, Sep 27, 2018 at 08:34:56PM +0200, Goffredo Baroncelli wrote: > > From: Goffredo Baroncelli <kreijack@inwind.it> > > > > Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it> > > Code LGTM. Though comment begs improvement. I will send you updated > comment for approval shortly. Below you can find updated patch. Please check I have not messed up something. Daniel From ecefb12a10d39bdd09e1d2b8fbbcbdb1b35274f8 Mon Sep 17 00:00:00 2001 From: Goffredo Baroncelli <kreijack@inwind.it> Date: Thu, 27 Sep 2018 20:34:56 +0200 Subject: [PATCH 1/1] btrfs: Add support for reading a filesystem with a RAID 5 or RAID 6 profile. Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it> Signed-off-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 be19544..933a57d 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; @@ -766,6 +768,77 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, 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: grub_dprintf ("btrfs", "unsupported RAID\n"); return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index be195448d..9bc6d399d 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 +766,78 @@ 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; + } + + /* + * A RAID 6 layout consists of several stripes spread on the + * disks, following a layout like the one below + * + * Disk0 Disk1 Disk2 Disk3 + * + * A1 B1 P1 Q1 + * Q2 A2 B2 P2 + * P3 Q3 A3 B3 + * [...] + * + * Note that the placement of the parities depends on row index. + * Pay attention that the BTRFS terminolgy may be different + * from others RAID implementation (e.g. lvm/dm or md). In BTRFS + * a contiguous block of data of a disk (like A1) is called + * stripe. + * In the code below: + * - stripe_nr is the stripe number without the parities + * (A1 = 0, B1 = 1, A2 = 2, B2 = 3, ...), + * - high is the row number (0 for A1...Q1, 1 for Q2...P2, ...), + * - stripen is the disk number in a row (0 for A1,Q2,P3, 1 for + * B1...), + * - off is the logical address to read, + * - chunk_stripe_length is the size of a stripe (typically 64k), + * - nstripes is the number of disks of 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 RAID5, 2 for + * RAID6); used only in RAID5/6 code. + */ + stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low); + + /* + * stripen is computed without the parities (0 for A1, A2, A3... + * 1 for B1, B2...). + */ + high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen); + + /* + * the stripes are spread across the disks, each row their + * position is shifted by 1 place. So to compute the real disk + * number occuped by a stripe, we need to sum also the + * "row number" in modulo nstripes (0 for A1, 1 for A2, 2 for + * A3....). + */ + grub_divmod64 (high + stripen, nstripes, &stripen); + + stripe_offset = low + chunk_stripe_length * high; + csize = chunk_stripe_length - low; + break; } default: