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NFS/flexfiles: Speed up read failover when DSes are down 

If we notice that a DS may be down, we should attempt to read from the
other mirrors first before we go back to retry the dead DS.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2019-02-14 17:32:40 -05:00
parent 17aaec8167
commit 76c6690522
3 changed files with 73 additions and 12 deletions
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70
fs/nfs/flexfilelayout/flexfilelayout.c
View File

@ -788,10 +788,28 @@ ff_layout_alloc_commit_info(struct pnfs_layout_segment *lseg,
}
}
static void
ff_layout_mark_ds_unreachable(struct pnfs_layout_segment *lseg, int idx)
{
struct nfs4_deviceid_node *devid = FF_LAYOUT_DEVID_NODE(lseg, idx);
if (devid)
nfs4_mark_deviceid_unavailable(devid);
}
static void
ff_layout_mark_ds_reachable(struct pnfs_layout_segment *lseg, int idx)
{
struct nfs4_deviceid_node *devid = FF_LAYOUT_DEVID_NODE(lseg, idx);
if (devid)
nfs4_mark_deviceid_available(devid);
}
static struct nfs4_pnfs_ds *
ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
int start_idx,
int *best_idx)
ff_layout_choose_ds_for_read(struct pnfs_layout_segment *lseg,
int start_idx, int *best_idx,
bool check_device)
{
struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
struct nfs4_ff_layout_mirror *mirror;
@ -799,25 +817,53 @@ ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
bool fail_return = false;
int idx;
/* mirrors are sorted by efficiency */
/* mirrors are initially sorted by efficiency */
for (idx = start_idx; idx < fls->mirror_array_cnt; idx++) {
if (idx+1 == fls->mirror_array_cnt)
fail_return = true;
fail_return = !check_device;
mirror = FF_LAYOUT_COMP(lseg, idx);
if (ff_layout_test_devid_unavailable(&mirror->mirror_ds->id_node))
ds = nfs4_ff_layout_prepare_ds(lseg, mirror, fail_return);
if (!ds)
continue;
if (check_device &&
nfs4_test_deviceid_unavailable(&mirror->mirror_ds->id_node))
continue;
ds = nfs4_ff_layout_prepare_ds(lseg, mirror, fail_return);
if (ds) {
*best_idx = idx;
return ds;
}
}
return NULL;
}
static struct nfs4_pnfs_ds *
ff_layout_choose_any_ds_for_read(struct pnfs_layout_segment *lseg,
int start_idx, int *best_idx)
{
return ff_layout_choose_ds_for_read(lseg, start_idx, best_idx, false);
}
static struct nfs4_pnfs_ds *
ff_layout_choose_valid_ds_for_read(struct pnfs_layout_segment *lseg,
int start_idx, int *best_idx)
{
return ff_layout_choose_ds_for_read(lseg, start_idx, best_idx, true);
}
static struct nfs4_pnfs_ds *
ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
int start_idx, int *best_idx)
{
struct nfs4_pnfs_ds *ds;
ds = ff_layout_choose_valid_ds_for_read(lseg, start_idx, best_idx);
if (ds)
return ds;
return ff_layout_choose_any_ds_for_read(lseg, start_idx, best_idx);
}
static void
ff_layout_pg_get_read(struct nfs_pageio_descriptor *pgio,
struct nfs_page *req,
@ -1167,8 +1213,10 @@ static int ff_layout_async_handle_error(struct rpc_task *task,
{
int vers = clp->cl_nfs_mod->rpc_vers->number;
if (task->tk_status >= 0)
if (task->tk_status >= 0) {
ff_layout_mark_ds_reachable(lseg, idx);
return 0;
}
/* Handle the case of an invalid layout segment */
if (!pnfs_is_valid_lseg(lseg))
@ -1231,6 +1279,8 @@ static void ff_layout_io_track_ds_error(struct pnfs_layout_segment *lseg,
err = ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
mirror, offset, length, status, opnum,
GFP_NOIO);
if (status == NFS4ERR_NXIO)
ff_layout_mark_ds_unreachable(lseg, idx);
pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode, lseg);
dprintk("%s: err %d op %d status %u\n", __func__, err, opnum, status);
}

1
fs/nfs/pnfs.h
View File

@ -350,6 +350,7 @@ void nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *, const struct nf
void nfs4_init_deviceid_node(struct nfs4_deviceid_node *, struct nfs_server *,
const struct nfs4_deviceid *);
bool nfs4_put_deviceid_node(struct nfs4_deviceid_node *);
void nfs4_mark_deviceid_available(struct nfs4_deviceid_node *node);
void nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node);
bool nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node);
void nfs4_deviceid_purge_client(const struct nfs_client *);

10
fs/nfs/pnfs_dev.c
View File

@ -283,6 +283,16 @@ nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
}
EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);
void
nfs4_mark_deviceid_available(struct nfs4_deviceid_node *node)
{
if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
smp_mb__after_atomic();
}
}
EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_available);
void
nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node)
{