ceph: add new mount option to enable sparse reads
Add a new mount option that has the client issue sparse reads instead of
normal ones. The callers now preallocate an sparse extent buffer that
the libceph receive code can populate and hand back after the operation
completes.
After a successful sparse read, we can't use the req->r_result value to
determine the amount of data "read", so instead we set the received
length to be from the end of the last extent in the buffer. Any
interstitial holes will have been filled by the receive code.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 752c421..15bc455 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -220,8 +220,10 @@
struct ceph_fs_client *fsc = ceph_inode_to_client(req->r_inode);
struct ceph_osd_data *osd_data = osd_req_op_extent_osd_data(req, 0);
struct netfs_read_subrequest *subreq = req->r_priv;
+ struct ceph_osd_req_op *op = &req->r_ops[0];
int num_pages;
int err = req->r_result;
+ bool sparse = (op->op == CEPH_OSD_OP_SPARSE_READ);
ceph_update_read_metrics(&fsc->mdsc->metric, req->r_start_latency,
req->r_end_latency, osd_data->length, err);
@@ -230,7 +232,9 @@
subreq->len, i_size_read(req->r_inode));
/* no object means success but no data */
- if (err == -ENOENT)
+ if (sparse && err >= 0)
+ err = ceph_sparse_ext_map_end(op);
+ else if (err == -ENOENT)
err = 0;
else if (err == -EBLOCKLISTED)
fsc->blocklisted = true;
@@ -311,13 +315,14 @@
size_t page_off;
int err = 0;
u64 len = subreq->len;
+ bool sparse = ceph_test_mount_opt(fsc, SPARSEREAD);
if (ci->i_inline_version != CEPH_INLINE_NONE &&
ceph_netfs_issue_op_inline(subreq))
return;
req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout, vino, subreq->start, &len,
- 0, 1, CEPH_OSD_OP_READ,
+ 0, 1, sparse ? CEPH_OSD_OP_SPARSE_READ : CEPH_OSD_OP_READ,
CEPH_OSD_FLAG_READ | fsc->client->osdc.client->options->read_from_replica,
NULL, ci->i_truncate_seq, ci->i_truncate_size, false);
if (IS_ERR(req)) {
@@ -326,6 +331,15 @@
goto out;
}
+ if (sparse) {
+ err = ceph_alloc_sparse_ext_map(&req->r_ops[0],
+ CEPH_SPARSE_EXT_ARRAY_INITIAL);
+ if (err) {
+ ceph_osdc_put_request(req);
+ goto out;
+ }
+ }
+
dout("%s: pos=%llu orig_len=%zu len=%llu\n", __func__, subreq->start, subreq->len, len);
iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages, subreq->start, len);
err = iov_iter_get_pages_alloc(&iter, &pages, len, &page_off);
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index feb75eb..3444a3b 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -905,6 +905,7 @@
u64 off = iocb->ki_pos;
u64 len = iov_iter_count(to);
u64 i_size = i_size_read(inode);
+ bool sparse = ceph_test_mount_opt(fsc, SPARSEREAD);
dout("sync_read on file %p %llu~%u %s\n", file, off, (unsigned)len,
(file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
@@ -931,10 +932,12 @@
bool more;
int idx;
size_t left;
+ struct ceph_osd_req_op *op;
req = ceph_osdc_new_request(osdc, &ci->i_layout,
ci->i_vino, off, &len, 0, 1,
- CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
+ sparse ? CEPH_OSD_OP_SPARSE_READ : CEPH_OSD_OP_READ,
+ CEPH_OSD_FLAG_READ,
NULL, ci->i_truncate_seq,
ci->i_truncate_size, false);
if (IS_ERR(req)) {
@@ -955,6 +958,16 @@
osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_off,
false, false);
+
+ op = &req->r_ops[0];
+ if (sparse) {
+ ret = ceph_alloc_sparse_ext_map(op, CEPH_SPARSE_EXT_ARRAY_INITIAL);
+ if (ret) {
+ ceph_osdc_put_request(req);
+ break;
+ }
+ }
+
ret = ceph_osdc_start_request(osdc, req, false);
if (!ret)
ret = ceph_osdc_wait_request(osdc, req);
@@ -964,19 +977,24 @@
req->r_end_latency,
len, ret);
- ceph_osdc_put_request(req);
-
i_size = i_size_read(inode);
dout("sync_read %llu~%llu got %zd i_size %llu%s\n",
off, len, ret, i_size, (more ? " MORE" : ""));
- if (ret == -ENOENT)
+ /* Fix it to go to end of extent map */
+ if (sparse && ret >= 0)
+ ret = ceph_sparse_ext_map_end(op);
+ else if (ret == -ENOENT)
ret = 0;
+
+ ceph_osdc_put_request(req);
+
if (ret >= 0 && ret < len && (off + ret < i_size)) {
int zlen = min(len - ret, i_size - off - ret);
int zoff = page_off + ret;
+
dout("sync_read zero gap %llu~%llu\n",
- off + ret, off + ret + zlen);
+ off + ret, off + ret + zlen);
ceph_zero_page_vector_range(zoff, zlen, pages);
ret += zlen;
}
@@ -1095,8 +1113,10 @@
struct inode *inode = req->r_inode;
struct ceph_aio_request *aio_req = req->r_priv;
struct ceph_osd_data *osd_data = osd_req_op_extent_osd_data(req, 0);
+ struct ceph_osd_req_op *op = &req->r_ops[0];
struct ceph_client_metric *metric = &ceph_sb_to_mdsc(inode->i_sb)->metric;
unsigned int len = osd_data->bvec_pos.iter.bi_size;
+ bool sparse = (op->op == CEPH_OSD_OP_SPARSE_READ);
BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_BVECS);
BUG_ON(!osd_data->num_bvecs);
@@ -1117,6 +1137,8 @@
}
rc = -ENOMEM;
} else if (!aio_req->write) {
+ if (sparse && rc >= 0)
+ rc = ceph_sparse_ext_map_end(op);
if (rc == -ENOENT)
rc = 0;
if (rc >= 0 && len > rc) {
@@ -1253,6 +1275,7 @@
loff_t pos = iocb->ki_pos;
bool write = iov_iter_rw(iter) == WRITE;
bool should_dirty = !write && iter_is_iovec(iter);
+ bool sparse = ceph_test_mount_opt(fsc, SPARSEREAD);
if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)
return -EROFS;
@@ -1280,6 +1303,8 @@
while (iov_iter_count(iter) > 0) {
u64 size = iov_iter_count(iter);
ssize_t len;
+ struct ceph_osd_req_op *op;
+ int readop = sparse ? CEPH_OSD_OP_SPARSE_READ : CEPH_OSD_OP_READ;
if (write)
size = min_t(u64, size, fsc->mount_options->wsize);
@@ -1290,8 +1315,7 @@
req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
vino, pos, &size, 0,
1,
- write ? CEPH_OSD_OP_WRITE :
- CEPH_OSD_OP_READ,
+ write ? CEPH_OSD_OP_WRITE : readop,
flags, snapc,
ci->i_truncate_seq,
ci->i_truncate_size,
@@ -1342,6 +1366,14 @@
}
osd_req_op_extent_osd_data_bvecs(req, 0, bvecs, num_pages, len);
+ op = &req->r_ops[0];
+ if (sparse) {
+ ret = ceph_alloc_sparse_ext_map(op, CEPH_SPARSE_EXT_ARRAY_INITIAL);
+ if (ret) {
+ ceph_osdc_put_request(req);
+ break;
+ }
+ }
if (aio_req) {
aio_req->total_len += len;
@@ -1370,8 +1402,11 @@
size = i_size_read(inode);
if (!write) {
- if (ret == -ENOENT)
+ if (sparse && ret >= 0)
+ ret = ceph_sparse_ext_map_end(op);
+ else if (ret == -ENOENT)
ret = 0;
+
if (ret >= 0 && ret < len && pos + ret < size) {
struct iov_iter i;
int zlen = min_t(size_t, len - ret,
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 978463f..a859921 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -163,6 +163,7 @@
Opt_copyfrom,
Opt_wsync,
Opt_pagecache,
+ Opt_sparseread,
};
enum ceph_recover_session_mode {
@@ -205,6 +206,7 @@
fsparam_u32 ("wsize", Opt_wsize),
fsparam_flag_no ("wsync", Opt_wsync),
fsparam_flag_no ("pagecache", Opt_pagecache),
+ fsparam_flag_no ("sparseread", Opt_sparseread),
{}
};
@@ -574,6 +576,12 @@
else
fsopt->flags &= ~CEPH_MOUNT_OPT_NOPAGECACHE;
break;
+ case Opt_sparseread:
+ if (result.negated)
+ fsopt->flags &= ~CEPH_MOUNT_OPT_SPARSEREAD;
+ else
+ fsopt->flags |= CEPH_MOUNT_OPT_SPARSEREAD;
+ break;
default:
BUG();
}
@@ -708,9 +716,10 @@
if (!(fsopt->flags & CEPH_MOUNT_OPT_ASYNC_DIROPS))
seq_puts(m, ",wsync");
-
if (fsopt->flags & CEPH_MOUNT_OPT_NOPAGECACHE)
seq_puts(m, ",nopagecache");
+ if (fsopt->flags & CEPH_MOUNT_OPT_SPARSEREAD)
+ seq_puts(m, ",sparseread");
if (fsopt->wsize != CEPH_MAX_WRITE_SIZE)
seq_printf(m, ",wsize=%u", fsopt->wsize);
@@ -1289,6 +1298,11 @@
else
ceph_clear_mount_opt(fsc, ASYNC_DIROPS);
+ if (fsopt->flags & CEPH_MOUNT_OPT_SPARSEREAD)
+ ceph_set_mount_opt(fsc, SPARSEREAD);
+ else
+ ceph_clear_mount_opt(fsc, SPARSEREAD);
+
if (strcmp_null(fsc->mount_options->mon_addr, fsopt->mon_addr)) {
kfree(fsc->mount_options->mon_addr);
fsc->mount_options->mon_addr = fsopt->mon_addr;
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 250aefe..4999207 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -43,6 +43,7 @@
#define CEPH_MOUNT_OPT_NOCOPYFROM (1<<14) /* don't use RADOS 'copy-from' op */
#define CEPH_MOUNT_OPT_ASYNC_DIROPS (1<<15) /* allow async directory ops */
#define CEPH_MOUNT_OPT_NOPAGECACHE (1<<16) /* bypass pagecache altogether */
+#define CEPH_MOUNT_OPT_SPARSEREAD (1<<17) /* always do sparse reads */
#define CEPH_MOUNT_OPT_DEFAULT \
(CEPH_MOUNT_OPT_DCACHE | \
@@ -75,6 +76,13 @@
#define CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT 5 /* cap release delay */
#define CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT 60 /* cap release delay */
+/*
+ * How big an extent array should we preallocate for a sparse read? This is
+ * just a starting value. If we get more than this back from the OSD, the
+ * receiver will reallocate.
+ */
+#define CEPH_SPARSE_EXT_ARRAY_INITIAL 16
+
struct ceph_mount_options {
unsigned int flags;
