diff options
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 49 |
1 files changed, 45 insertions, 4 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 13d76767c2cf..dc83da69ca7c 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2897,6 +2897,30 @@ sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous) return r_sector; } +/* + * There are cases where we want handle_stripe_dirtying() and + * schedule_reconstruction() to delay towrite to some dev of a stripe. + * + * This function checks whether we want to delay the towrite. Specifically, + * we delay the towrite when: + * + * 1. degraded stripe has a non-overwrite to the missing dev, AND this + * stripe has data in journal (for other devices). + * + * In this case, when reading data for the non-overwrite dev, it is + * necessary to handle complex rmw of write back cache (prexor with + * orig_page, and xor with page). To keep read path simple, we would + * like to flush data in journal to RAID disks first, so complex rmw + * is handled in the write patch (handle_stripe_dirtying). + * + */ +static inline bool delay_towrite(struct r5dev *dev, + struct stripe_head_state *s) +{ + return !test_bit(R5_OVERWRITE, &dev->flags) && + !test_bit(R5_Insync, &dev->flags) && s->injournal; +} + static void schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, int rcw, int expand) @@ -2917,7 +2941,7 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, for (i = disks; i--; ) { struct r5dev *dev = &sh->dev[i]; - if (dev->towrite) { + if (dev->towrite && !delay_towrite(dev, s)) { set_bit(R5_LOCKED, &dev->flags); set_bit(R5_Wantdrain, &dev->flags); if (!expand) @@ -3494,10 +3518,26 @@ static void handle_stripe_fill(struct stripe_head *sh, * midst of changing due to a write */ if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state && - !sh->reconstruct_state) + !sh->reconstruct_state) { + + /* + * For degraded stripe with data in journal, do not handle + * read requests yet, instead, flush the stripe to raid + * disks first, this avoids handling complex rmw of write + * back cache (prexor with orig_page, and then xor with + * page) in the read path + */ + if (s->injournal && s->failed) { + if (test_bit(STRIPE_R5C_CACHING, &sh->state)) + r5c_make_stripe_write_out(sh); + goto out; + } + for (i = disks; i--; ) if (fetch_block(sh, s, i, disks)) break; + } +out: set_bit(STRIPE_HANDLE, &sh->state); } @@ -3653,7 +3693,8 @@ static int handle_stripe_dirtying(struct r5conf *conf, } else for (i = disks; i--; ) { /* would I have to read this buffer for read_modify_write */ struct r5dev *dev = &sh->dev[i]; - if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx || + if (((dev->towrite && !delay_towrite(dev, s)) || + i == sh->pd_idx || i == sh->qd_idx || test_bit(R5_InJournal, &dev->flags)) && !test_bit(R5_LOCKED, &dev->flags) && !(uptodate_for_rmw(dev) || @@ -3717,7 +3758,7 @@ static int handle_stripe_dirtying(struct r5conf *conf, for (i = disks; i--; ) { struct r5dev *dev = &sh->dev[i]; - if ((dev->towrite || + if (((dev->towrite && !delay_towrite(dev, s)) || i == sh->pd_idx || i == sh->qd_idx || test_bit(R5_InJournal, &dev->flags)) && !test_bit(R5_LOCKED, &dev->flags) && |