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Skip spurious resilver IO on raidz vdev 

On a raidz vdev, a block that does not span all child vdevs, excluding
its skip sectors if any, may not be affected by a child vdev outage or
failure. In such cases, the block does not need to be resilvered.
However, current resilver algorithm simply resilvers all blocks on a
degraded raidz vdev. Such spurious IO is not only wasteful, but also
adds the risk of overwriting good data.

This patch eliminates such spurious IOs.

Reviewed-by: Gvozden Neskovic <neskovic@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Isaac Huang <he.huang@intel.com>
Closes #5316
This commit is contained in:
Isaac Huang 2017-05-12 18:28:03 -06:00 committed by Brian Behlendorf
parent 8c54ddd33a
commit 3d6da72d18
10 changed files with 125 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/sys/vdev.h
View File

@ -65,6 +65,7 @@ extern void vdev_dtl_dirty(vdev_t *vd, vdev_dtl_type_t d,
extern boolean_t vdev_dtl_contains(vdev_t *vd, vdev_dtl_type_t d,
uint64_t txg, uint64_t size);
extern boolean_t vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t d);
extern boolean_t vdev_dtl_need_resilver(vdev_t *vd, uint64_t off, size_t size);
extern void vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
int scrub_done);
extern boolean_t vdev_dtl_required(vdev_t *vd);

2
include/sys/vdev_impl.h
View File

@ -68,6 +68,7 @@ typedef uint64_t vdev_asize_func_t(vdev_t *vd, uint64_t psize);
typedef void vdev_io_start_func_t(zio_t *zio);
typedef void vdev_io_done_func_t(zio_t *zio);
typedef void vdev_state_change_func_t(vdev_t *vd, int, int);
typedef boolean_t vdev_need_resilver_func_t(vdev_t *vd, uint64_t, size_t);
typedef void vdev_hold_func_t(vdev_t *vd);
typedef void vdev_rele_func_t(vdev_t *vd);
@ -78,6 +79,7 @@ typedef const struct vdev_ops {
vdev_io_start_func_t *vdev_op_io_start;
vdev_io_done_func_t *vdev_op_io_done;
vdev_state_change_func_t *vdev_op_state_change;
vdev_need_resilver_func_t *vdev_op_need_resilver;
vdev_hold_func_t *vdev_op_hold;
vdev_rele_func_t *vdev_op_rele;
char vdev_op_type[16];

72
module/zfs/dsl_scan.c
View File

@ -1836,12 +1836,51 @@ dsl_scan_scrub_done(zio_t *zio)
mutex_exit(&spa->spa_scrub_lock);
}
static boolean_t
dsl_scan_need_resilver(spa_t *spa, const dva_t *dva, size_t psize,
uint64_t phys_birth)
{
vdev_t *vd;
if (DVA_GET_GANG(dva)) {
/*
* Gang members may be spread across multiple
* vdevs, so the best estimate we have is the
* scrub range, which has already been checked.
* XXX -- it would be better to change our
* allocation policy to ensure that all
* gang members reside on the same vdev.
*/
return (B_TRUE);
}
vd = vdev_lookup_top(spa, DVA_GET_VDEV(dva));
/*
* Check if the txg falls within the range which must be
* resilvered. DVAs outside this range can always be skipped.
*/
if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1))
return (B_FALSE);
/*
* Check if the top-level vdev must resilver this offset.
* When the offset does not intersect with a dirty leaf DTL
* then it may be possible to skip the resilver IO. The psize
* is provided instead of asize to simplify the check for RAIDZ.
*/
if (!vdev_dtl_need_resilver(vd, DVA_GET_OFFSET(dva), psize))
return (B_FALSE);
return (B_TRUE);
}
static int
dsl_scan_scrub_cb(dsl_pool_t *dp,
const blkptr_t *bp, const zbookmark_phys_t *zb)
{
dsl_scan_t *scn = dp->dp_scan;
size_t size = BP_GET_PSIZE(bp);
size_t psize = BP_GET_PSIZE(bp);
spa_t *spa = dp->dp_spa;
uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
boolean_t needs_io = B_FALSE;
@ -1875,33 +1914,19 @@ dsl_scan_scrub_cb(dsl_pool_t *dp,
zio_flags |= ZIO_FLAG_SPECULATIVE;
for (d = 0; d < BP_GET_NDVAS(bp); d++) {
vdev_t *vd = vdev_lookup_top(spa,
DVA_GET_VDEV(&bp->blk_dva[d]));
const dva_t *dva = &bp->blk_dva[d];
/*
* Keep track of how much data we've examined so that
* zpool(1M) status can make useful progress reports.
*/
scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
scn->scn_phys.scn_examined += DVA_GET_ASIZE(dva);
spa->spa_scan_pass_exam += DVA_GET_ASIZE(dva);
/* if it's a resilver, this may not be in the target range */
if (!needs_io) {
if (DVA_GET_GANG(&bp->blk_dva[d])) {
/*
* Gang members may be spread across multiple
* vdevs, so the best estimate we have is the
* scrub range, which has already been checked.
* XXX -- it would be better to change our
* allocation policy to ensure that all
* gang members reside on the same vdev.
*/
needs_io = B_TRUE;
} else {
needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
phys_birth, 1);
}
}
if (!needs_io)
needs_io = dsl_scan_need_resilver(spa, dva, psize,
phys_birth);
}
if (needs_io && !zfs_no_scrub_io) {
@ -1922,8 +1947,9 @@ dsl_scan_scrub_cb(dsl_pool_t *dp,
delay(scan_delay);
zio_nowait(zio_read(NULL, spa, bp,
abd_alloc_for_io(size, B_FALSE), size, dsl_scan_scrub_done,
NULL, ZIO_PRIORITY_SCRUB, zio_flags, zb));
abd_alloc_for_io(psize, B_FALSE),
psize, dsl_scan_scrub_done, NULL,
ZIO_PRIORITY_SCRUB, zio_flags, zb));
}
/* do not relocate this block */

15
module/zfs/vdev.c
View File

@ -1819,6 +1819,21 @@ vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t t)
return (empty);
}
/*
* Returns B_TRUE if vdev determines offset needs to be resilvered.
*/
boolean_t
vdev_dtl_need_resilver(vdev_t *vd, uint64_t offset, size_t psize)
{
ASSERT(vd != vd->vdev_spa->spa_root_vdev);
if (vd->vdev_ops->vdev_op_need_resilver == NULL ||
vd->vdev_ops->vdev_op_leaf)
return (B_TRUE);
return (vd->vdev_ops->vdev_op_need_resilver(vd, offset, psize));
}
/*
* Returns the lowest txg in the DTL range.
*/

1
module/zfs/vdev_disk.c
View File

@ -796,6 +796,7 @@ vdev_ops_t vdev_disk_ops = {
vdev_disk_io_start,
vdev_disk_io_done,
NULL,
NULL,
vdev_disk_hold,
vdev_disk_rele,
VDEV_TYPE_DISK, /* name of this vdev type */

2
module/zfs/vdev_file.c
View File

@ -250,6 +250,7 @@ vdev_ops_t vdev_file_ops = {
vdev_file_io_start,
vdev_file_io_done,
NULL,
NULL,
vdev_file_hold,
vdev_file_rele,
VDEV_TYPE_FILE, /* name of this vdev type */
@ -283,6 +284,7 @@ vdev_ops_t vdev_disk_ops = {
vdev_file_io_start,
vdev_file_io_done,
NULL,
NULL,
vdev_file_hold,
vdev_file_rele,
VDEV_TYPE_DISK, /* name of this vdev type */

3
module/zfs/vdev_mirror.c
View File

@ -615,6 +615,7 @@ vdev_ops_t vdev_mirror_ops = {
vdev_mirror_state_change,
NULL,
NULL,
NULL,
VDEV_TYPE_MIRROR, /* name of this vdev type */
B_FALSE /* not a leaf vdev */
};
@ -628,6 +629,7 @@ vdev_ops_t vdev_replacing_ops = {
vdev_mirror_state_change,
NULL,
NULL,
NULL,
VDEV_TYPE_REPLACING, /* name of this vdev type */
B_FALSE /* not a leaf vdev */
};
@ -641,6 +643,7 @@ vdev_ops_t vdev_spare_ops = {
vdev_mirror_state_change,
NULL,
NULL,
NULL,
VDEV_TYPE_SPARE, /* name of this vdev type */
B_FALSE /* not a leaf vdev */
};

2
module/zfs/vdev_missing.c
View File

@ -88,6 +88,7 @@ vdev_ops_t vdev_missing_ops = {
NULL,
NULL,
NULL,
NULL,
VDEV_TYPE_MISSING, /* name of this vdev type */
B_TRUE /* leaf vdev */
};
@ -101,6 +102,7 @@ vdev_ops_t vdev_hole_ops = {
NULL,
NULL,
NULL,
NULL,
VDEV_TYPE_HOLE, /* name of this vdev type */
B_TRUE /* leaf vdev */
};

59
module/zfs/vdev_raidz.c
View File

@ -330,18 +330,18 @@ static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
* is this functions only caller, as small as possible on the stack.
*/
noinline raidz_map_t *
vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
vdev_raidz_map_alloc(zio_t *zio, uint64_t ashift, uint64_t dcols,
uint64_t nparity)
{
raidz_map_t *rm;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = zio->io_offset >> unit_shift;
uint64_t b = zio->io_offset >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = zio->io_size >> unit_shift;
uint64_t s = zio->io_size >> ashift;
/* The first column for this stripe. */
uint64_t f = b % dcols;
/* The starting byte offset on each child vdev. */
uint64_t o = (b / dcols) << unit_shift;
uint64_t o = (b / dcols) << ashift;
uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot;
uint64_t off = 0;
@ -400,7 +400,7 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
coff = o;
if (col >= dcols) {
col -= dcols;
coff += 1ULL << unit_shift;
coff += 1ULL << ashift;
}
rm->rm_col[c].rc_devidx = col;
rm->rm_col[c].rc_offset = coff;
@ -413,17 +413,17 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
if (c >= acols)
rm->rm_col[c].rc_size = 0;
else if (c < bc)
rm->rm_col[c].rc_size = (q + 1) << unit_shift;
rm->rm_col[c].rc_size = (q + 1) << ashift;
else
rm->rm_col[c].rc_size = q << unit_shift;
rm->rm_col[c].rc_size = q << ashift;
asize += rm->rm_col[c].rc_size;
}
ASSERT3U(asize, ==, tot << unit_shift);
rm->rm_asize = roundup(asize, (nparity + 1) << unit_shift);
ASSERT3U(asize, ==, tot << ashift);
rm->rm_asize = roundup(asize, (nparity + 1) << ashift);
rm->rm_nskip = roundup(tot, nparity + 1) - tot;
ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << unit_shift);
ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << ashift);
ASSERT3U(rm->rm_nskip, <=, nparity);
for (c = 0; c < rm->rm_firstdatacol; c++)
@ -2299,6 +2299,44 @@ vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded)
vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
}
/*
* Determine if any portion of the provided block resides on a child vdev
* with a dirty DTL and therefore needs to be resilvered. The function
* assumes that at least one DTL is dirty which imples that full stripe
* width blocks must be resilvered.
*/
static boolean_t
vdev_raidz_need_resilver(vdev_t *vd, uint64_t offset, size_t psize)
{
uint64_t dcols = vd->vdev_children;
uint64_t nparity = vd->vdev_nparity;
uint64_t ashift = vd->vdev_top->vdev_ashift;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = offset >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = ((psize - 1) >> ashift) + 1;
/* The first column for this stripe. */
uint64_t f = b % dcols;
if (s + nparity >= dcols)
return (B_TRUE);
for (uint64_t c = 0; c < s + nparity; c++) {
uint64_t devidx = (f + c) % dcols;
vdev_t *cvd = vd->vdev_child[devidx];
/*
* dsl_scan_need_resilver() already checked vd with
* vdev_dtl_contains(). So here just check cvd with
* vdev_dtl_empty(), cheaper and a good approximation.
*/
if (!vdev_dtl_empty(cvd, DTL_PARTIAL))
return (B_TRUE);
}
return (B_FALSE);
}
vdev_ops_t vdev_raidz_ops = {
vdev_raidz_open,
vdev_raidz_close,
@ -2306,6 +2344,7 @@ vdev_ops_t vdev_raidz_ops = {
vdev_raidz_io_start,
vdev_raidz_io_done,
vdev_raidz_state_change,
vdev_raidz_need_resilver,
NULL,
NULL,
VDEV_TYPE_RAIDZ, /* name of this vdev type */

1
module/zfs/vdev_root.c
View File

@ -120,6 +120,7 @@ vdev_ops_t vdev_root_ops = {
vdev_root_state_change,
NULL,
NULL,
NULL,
VDEV_TYPE_ROOT, /* name of this vdev type */
B_FALSE /* not a leaf vdev */
};