| Message ID | 20201026071115.57225-5-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: scrub: support subpage scrub (completely independent version) | expand |
On 10/26/20 3:11 AM, Qu Wenruo wrote: > Function scrub_find_csum() is to locate the csum for bytenr @logical > from sctx->csum_list. > > However it lacks a lot of comments to explaining things like how the > csum_list is organized and why we need to drop csum range which is > before us. > > Refactor the function by: > - Add more comment explaining the behavior > - Add comment explaining why we need to drop the csum range > - Put the csum copy in the main loop > This is mostly for the incoming patches to make scrub_find_csum() able > to find multiple checksums. > > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > fs/btrfs/scrub.c | 70 +++++++++++++++++++++++++++++++++++------------- > 1 file changed, 51 insertions(+), 19 deletions(-) > > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c > index 321d6d457942..0d078393f986 100644 > --- a/fs/btrfs/scrub.c > +++ b/fs/btrfs/scrub.c > @@ -2386,37 +2386,69 @@ static void scrub_block_complete(struct scrub_block *sblock) > } > } > > +static void drop_csum_range(struct scrub_ctx *sctx, > + struct btrfs_ordered_sum *sum) > +{ > + u32 sectorsize = sctx->fs_info->sectorsize; > + > + sctx->stat.csum_discards += sum->len / sectorsize; > + list_del(&sum->list); > + kfree(sum); > +} > + > +/* > + * Find the desired csum for range [@logical, @logical + sectorsize), and > + * store the csum into @csum. > + * > + * The search source is sctx->csum_list, which is a pre-populated list > + * storing bytenr ordered csum ranges. > + * We're reponsible to cleanup any range that is before @logical. > + * > + * Return 0 if there is no csum for the range. > + * Return 1 if there is csum for the range and copied to @csum. > + */ > static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum) > { > - struct btrfs_ordered_sum *sum = NULL; > - unsigned long index; > - unsigned long num_sectors; > + u32 sectorsize = sctx->fs_info->sectorsize; > + u32 csum_size = sctx->csum_size; > + bool found = false; > > while (!list_empty(&sctx->csum_list)) { > + struct btrfs_ordered_sum *sum = NULL; > + unsigned long index; > + unsigned long num_sectors; > + > sum = list_first_entry(&sctx->csum_list, > struct btrfs_ordered_sum, list); > + /* The current csum range is beyond our range, no csum found */ > if (sum->bytenr > logical) > - return 0; > - if (sum->bytenr + sum->len > logical) > break; > > - ++sctx->stat.csum_discards; > - list_del(&sum->list); > - kfree(sum); > - sum = NULL; > - } > - if (!sum) > - return 0; > + /* > + * The current sum is before our bytenr, since scrub is > + * always done in bytenr order, the csum will never be used > + * anymore, clean it up so that later calls won't bother the > + * range, and continue search the next range. > + */ > + if (sum->bytenr + sum->len <= logical) { > + drop_csum_range(sctx, sum); > + continue; > + } > > - index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize); > - ASSERT(index < UINT_MAX); > + /* Now the csum range covers our bytenr, copy the csum */ > + found = true; > + index = div_u64(logical - sum->bytenr, sectorsize); > + num_sectors = sum->len / sectorsize; > > - num_sectors = sum->len / sctx->fs_info->sectorsize; > - memcpy(csum, sum->sums + index * sctx->csum_size, sctx->csum_size); > - if (index == num_sectors - 1) { > - list_del(&sum->list); > - kfree(sum); > + memcpy(csum, sum->sums + index * csum_size, csum_size); > + > + /* Cleanup the range if we're at the end of the csum range */ > + if (index == num_sectors - 1) > + drop_csum_range(sctx, sum); > + break; > } > + if (!found) > + return 0; > return 1; > } If it's just a bool we're returning, change this to static bool scrub_find_csum() and do return found. Thanks, Josef
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 321d6d457942..0d078393f986 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2386,37 +2386,69 @@ static void scrub_block_complete(struct scrub_block *sblock) } } +static void drop_csum_range(struct scrub_ctx *sctx, + struct btrfs_ordered_sum *sum) +{ + u32 sectorsize = sctx->fs_info->sectorsize; + + sctx->stat.csum_discards += sum->len / sectorsize; + list_del(&sum->list); + kfree(sum); +} + +/* + * Find the desired csum for range [@logical, @logical + sectorsize), and + * store the csum into @csum. + * + * The search source is sctx->csum_list, which is a pre-populated list + * storing bytenr ordered csum ranges. + * We're reponsible to cleanup any range that is before @logical. + * + * Return 0 if there is no csum for the range. + * Return 1 if there is csum for the range and copied to @csum. + */ static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum) { - struct btrfs_ordered_sum *sum = NULL; - unsigned long index; - unsigned long num_sectors; + u32 sectorsize = sctx->fs_info->sectorsize; + u32 csum_size = sctx->csum_size; + bool found = false; while (!list_empty(&sctx->csum_list)) { + struct btrfs_ordered_sum *sum = NULL; + unsigned long index; + unsigned long num_sectors; + sum = list_first_entry(&sctx->csum_list, struct btrfs_ordered_sum, list); + /* The current csum range is beyond our range, no csum found */ if (sum->bytenr > logical) - return 0; - if (sum->bytenr + sum->len > logical) break; - ++sctx->stat.csum_discards; - list_del(&sum->list); - kfree(sum); - sum = NULL; - } - if (!sum) - return 0; + /* + * The current sum is before our bytenr, since scrub is + * always done in bytenr order, the csum will never be used + * anymore, clean it up so that later calls won't bother the + * range, and continue search the next range. + */ + if (sum->bytenr + sum->len <= logical) { + drop_csum_range(sctx, sum); + continue; + } - index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize); - ASSERT(index < UINT_MAX); + /* Now the csum range covers our bytenr, copy the csum */ + found = true; + index = div_u64(logical - sum->bytenr, sectorsize); + num_sectors = sum->len / sectorsize; - num_sectors = sum->len / sctx->fs_info->sectorsize; - memcpy(csum, sum->sums + index * sctx->csum_size, sctx->csum_size); - if (index == num_sectors - 1) { - list_del(&sum->list); - kfree(sum); + memcpy(csum, sum->sums + index * csum_size, csum_size); + + /* Cleanup the range if we're at the end of the csum range */ + if (index == num_sectors - 1) + drop_csum_range(sctx, sum); + break; } + if (!found) + return 0; return 1; }
Function scrub_find_csum() is to locate the csum for bytenr @logical from sctx->csum_list. However it lacks a lot of comments to explaining things like how the csum_list is organized and why we need to drop csum range which is before us. Refactor the function by: - Add more comment explaining the behavior - Add comment explaining why we need to drop the csum range - Put the csum copy in the main loop This is mostly for the incoming patches to make scrub_find_csum() able to find multiple checksums. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/scrub.c | 70 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 51 insertions(+), 19 deletions(-)