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bcachefs: bch_member->seq

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Add new fields for split brain detection:

 - bch_member->seq, which tracks the sequence number of the last superblock
   write that happened to each member device

 - bch_sb->write_time, which tracks the time of the last superblock write,
   to allow detection of when two members have diverged but had the same
   number of superblock writes.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-06-27 21:02:27 -04:00
parent 62719cf33c
commit 6b00de06f5
3 changed files with 22 additions and 2 deletions
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8
fs/bcachefs/bcachefs_format.h
View File

@ -1303,6 +1303,7 @@ struct bch_member {
__le64 errors[BCH_MEMBER_ERROR_NR];
__le64 errors_at_reset[BCH_MEMBER_ERROR_NR];
__le64 errors_reset_time;
__le64 seq;
};
#define BCH_MEMBER_V1_BYTES 56
@ -1729,7 +1730,9 @@ struct bch_sb_field_downgrade {
x(deleted_inodes, BCH_VERSION(1, 2), \
BIT_ULL(BCH_RECOVERY_PASS_check_inodes)) \
x(rebalance_work, BCH_VERSION(1, 3), \
BIT_ULL(BCH_RECOVERY_PASS_set_fs_needs_rebalance))
BIT_ULL(BCH_RECOVERY_PASS_set_fs_needs_rebalance)) \
x(member_seq, BCH_VERSION(1, 4), \
0)
enum bcachefs_metadata_version {
bcachefs_metadata_version_min = 9,
@ -1795,7 +1798,8 @@ struct bch_sb {
__le32 time_base_hi;
__le32 time_precision;
__le64 flags[8];
__le64 flags[7];
__le64 write_time;
__le64 features[2];
__le64 compat[2];

5
fs/bcachefs/sb-members.c
View File

@ -235,6 +235,11 @@ static void member_to_text(struct printbuf *out,
prt_printf(out, "(never)");
prt_newline(out);
prt_printf(out, "Last superblock write:");
prt_tab(out);
prt_u64(out, le64_to_cpu(m.seq));
prt_newline(out);
prt_printf(out, "State:");
prt_tab(out);
prt_printf(out, "%s",

11
fs/bcachefs/super-io.c
View File

@ -564,6 +564,7 @@ static int __copy_super(struct bch_sb_handle *dst_handle, struct bch_sb *src)
dst->time_base_lo = src->time_base_lo;
dst->time_base_hi = src->time_base_hi;
dst->time_precision = src->time_precision;
dst->write_time = src->write_time;
memcpy(dst->flags, src->flags, sizeof(dst->flags));
memcpy(dst->features, src->features, sizeof(dst->features));
@ -942,6 +943,11 @@ int bch2_write_super(struct bch_fs *c)
le64_add_cpu(&c->disk_sb.sb->seq, 1);
struct bch_sb_field_members_v2 *mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
for_each_online_member(c, ca)
__bch2_members_v2_get_mut(mi, ca->dev_idx)->seq = c->disk_sb.sb->seq;
c->disk_sb.sb->write_time = cpu_to_le64(ktime_get_real_seconds());
if (test_bit(BCH_FS_error, &c->flags))
SET_BCH_SB_HAS_ERRORS(c->disk_sb.sb, 1);
if (test_bit(BCH_FS_topology_error, &c->flags))
@ -1304,6 +1310,11 @@ void bch2_sb_to_text(struct printbuf *out, struct bch_sb *sb,
prt_printf(out, "%llu", le64_to_cpu(sb->seq));
prt_newline(out);
prt_printf(out, "Time of last write:");
prt_tab(out);
bch2_prt_datetime(out, le64_to_cpu(sb->write_time));
prt_newline(out);
prt_printf(out, "Superblock size:");
prt_tab(out);
prt_printf(out, "%zu", vstruct_bytes(sb));