ore: Only IO one group at a time (API change)
Usually a single IO is confined to one group of devices
(group_width) and at the boundary of a raid group it can
spill into a second group. Current code would allocate a
full device_table size array at each io_state so it can
comply to requests that span two groups. Needless to say
that is very wasteful, specially when device_table count
can get very large (hundreds even thousands), while a
group_width is usually 8 or 10.
* Change ore API to trim on IO that spans two raid groups.
The user passes offset+length to ore_get_rw_state, the
ore might trim on that length if spanning a group boundary.
The user must check ios->length or ios->nrpages to see
how much IO will be preformed. It is the responsibility
of the user to re-issue the reminder of the IO.
* Modify exofs To copy spilled pages on to the next IO.
This means one last kick is needed after all coalescing
of pages is done.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
index a7d7925..c1c2cc6 100644
--- a/fs/exofs/ore.c
+++ b/fs/exofs/ore.c
@@ -47,6 +47,9 @@
MODULE_DESCRIPTION("Objects Raid Engine ore.ko");
MODULE_LICENSE("GPL");
+static void ore_calc_stripe_info(struct ore_layout *layout, u64 file_offset,
+ struct ore_striping_info *si);
+
static u8 *_ios_cred(struct ore_io_state *ios, unsigned index)
{
return ios->oc->comps[index & ios->oc->single_comp].cred;
@@ -62,38 +65,85 @@
return ore_comp_dev(ios->oc, index);
}
-int ore_get_rw_state(struct ore_layout *layout, struct ore_components *oc,
- bool is_reading, u64 offset, u64 length,
- struct ore_io_state **pios)
+static int _get_io_state(struct ore_layout *layout,
+ struct ore_components *oc, unsigned numdevs,
+ struct ore_io_state **pios)
{
struct ore_io_state *ios;
/*TODO: Maybe use kmem_cach per sbi of size
* exofs_io_state_size(layout->s_numdevs)
*/
- ios = kzalloc(ore_io_state_size(oc->numdevs), GFP_KERNEL);
+ ios = kzalloc(ore_io_state_size(numdevs), GFP_KERNEL);
if (unlikely(!ios)) {
ORE_DBGMSG("Failed kzalloc bytes=%d\n",
- ore_io_state_size(oc->numdevs));
+ ore_io_state_size(numdevs));
*pios = NULL;
return -ENOMEM;
}
ios->layout = layout;
ios->oc = oc;
- ios->offset = offset;
- ios->length = length;
- ios->reading = is_reading;
-
*pios = ios;
return 0;
}
+
+/* Allocate an io_state for only a single group of devices
+ *
+ * If a user needs to call ore_read/write() this version must be used becase it
+ * allocates extra stuff for striping and raid.
+ * The ore might decide to only IO less then @length bytes do to alignmets
+ * and constrains as follows:
+ * - The IO cannot cross group boundary.
+ * - In raid5/6 The end of the IO must align at end of a stripe eg.
+ * (@offset + @length) % strip_size == 0. Or the complete range is within a
+ * single stripe.
+ * - Memory condition only permitted a shorter IO. (A user can use @length=~0
+ * And check the returned ios->length for max_io_size.)
+ *
+ * The caller must check returned ios->length (and/or ios->nr_pages) and
+ * re-issue these pages that fall outside of ios->length
+ */
+int ore_get_rw_state(struct ore_layout *layout, struct ore_components *oc,
+ bool is_reading, u64 offset, u64 length,
+ struct ore_io_state **pios)
+{
+ struct ore_io_state *ios;
+ unsigned numdevs = layout->group_width * layout->mirrors_p1;
+ int ret;
+
+ ret = _get_io_state(layout, oc, numdevs, pios);
+ if (unlikely(ret))
+ return ret;
+
+ ios = *pios;
+ ios->reading = is_reading;
+ ios->offset = offset;
+
+ if (length) {
+ struct ore_striping_info si;
+
+ ore_calc_stripe_info(layout, offset, &si);
+ ios->length = (length <= si.group_length) ? length :
+ si.group_length;
+ ios->nr_pages = (ios->length + PAGE_SIZE - 1) / PAGE_SIZE;
+ }
+
+ return 0;
+}
EXPORT_SYMBOL(ore_get_rw_state);
+/* Allocate an io_state for all the devices in the comps array
+ *
+ * This version of io_state allocation is used mostly by create/remove
+ * and trunc where we currently need all the devices. The only wastful
+ * bit is the read/write_attributes with no IO. Those sites should
+ * be converted to use ore_get_rw_state() with length=0
+ */
int ore_get_io_state(struct ore_layout *layout, struct ore_components *oc,
- struct ore_io_state **ios)
+ struct ore_io_state **pios)
{
- return ore_get_rw_state(layout, oc, true, 0, 0, ios);
+ return _get_io_state(layout, oc, oc->numdevs, pios);
}
EXPORT_SYMBOL(ore_get_io_state);
@@ -374,12 +424,12 @@
unsigned devs_in_group = ios->layout->group_width * mirrors_p1;
unsigned dev = si->dev;
unsigned first_dev = dev - (dev % devs_in_group);
- unsigned max_comp = ios->numdevs ? ios->numdevs - mirrors_p1 : 0;
unsigned cur_pg = ios->pages_consumed;
int ret = 0;
while (length) {
- struct ore_per_dev_state *per_dev = &ios->per_dev[dev];
+ unsigned comp = dev - first_dev;
+ struct ore_per_dev_state *per_dev = &ios->per_dev[comp];
unsigned cur_len, page_off = 0;
if (!per_dev->length) {
@@ -397,9 +447,6 @@
per_dev->offset = si->obj_offset - si->unit_off;
cur_len = stripe_unit;
}
-
- if (max_comp < dev)
- max_comp = dev;
} else {
cur_len = stripe_unit;
}
@@ -417,17 +464,15 @@
length -= cur_len;
}
out:
- ios->numdevs = max_comp + mirrors_p1;
+ ios->numdevs = devs_in_group;
ios->pages_consumed = cur_pg;
return ret;
}
static int _prepare_for_striping(struct ore_io_state *ios)
{
- u64 length = ios->length;
- u64 offset = ios->offset;
struct ore_striping_info si;
- int ret = 0;
+ int ret;
if (!ios->pages) {
if (ios->kern_buff) {
@@ -446,21 +491,11 @@
return 0;
}
- while (length) {
- ore_calc_stripe_info(ios->layout, offset, &si);
+ ore_calc_stripe_info(ios->layout, ios->offset, &si);
- if (length < si.group_length)
- si.group_length = length;
+ BUG_ON(ios->length > si.group_length);
+ ret = _prepare_one_group(ios, ios->length, &si);
- ret = _prepare_one_group(ios, si.group_length, &si);
- if (unlikely(ret))
- goto out;
-
- offset += si.group_length;
- length -= si.group_length;
- }
-
-out:
return ret;
}
@@ -742,7 +777,6 @@
unsigned first_group_dev;
unsigned nex_group_dev;
- unsigned max_devs;
};
static void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
@@ -757,7 +791,6 @@
ti->first_group_dev = ti->si.dev - (ti->si.dev % layout->group_width);
ti->nex_group_dev = ti->first_group_dev + layout->group_width;
- ti->max_devs = layout->group_width * layout->group_count;
}
int ore_truncate(struct ore_layout *layout, struct ore_components *oc,
@@ -777,7 +810,7 @@
_calc_trunk_info(ios->layout, size, &ti);
- size_attrs = kcalloc(ti.max_devs, sizeof(*size_attrs),
+ size_attrs = kcalloc(ios->oc->numdevs, sizeof(*size_attrs),
GFP_KERNEL);
if (unlikely(!size_attrs)) {
ret = -ENOMEM;
@@ -786,7 +819,7 @@
ios->numdevs = ios->oc->numdevs;
- for (i = 0; i < ti.max_devs; ++i) {
+ for (i = 0; i < ios->numdevs; ++i) {
struct exofs_trunc_attr *size_attr = &size_attrs[i];
u64 obj_size;
