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Subject[21/49] ore: Must support none-PAGE-aligned IO
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Boaz Harrosh <bharrosh@panasas.com>

commit 724577ca355795b0a25c93ccbeee927871ca1a77 upstream.

NFS might send us offsets that are not PAGE aligned. So
we must read in the reminder of the first/last pages, in cases
we need it for Parity calculations.

We only add an sg segments to read the partial page. But
we don't mark it as read=true because it is a lock-for-write
page.

TODO: In some cases (IO spans a single unit) we can just
adjust the raid_unit offset/length, but this is left for
later Kernels.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/exofs/ore_raid.c | 72 +++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 60 insertions(+), 12 deletions(-)
--- a/fs/exofs/ore_raid.c
+++ b/fs/exofs/ore_raid.c
@@ -328,8 +328,8 @@ static int _alloc_read_4_write(struct or
/* @si contains info of the to-be-inserted page. Update of @si should be
* maintained by caller. Specificaly si->dev, si->obj_offset, ...
*/
-static int _add_to_read_4_write(struct ore_io_state *ios,
- struct ore_striping_info *si, struct page *page)
+static int _add_to_r4w(struct ore_io_state *ios, struct ore_striping_info *si,
+ struct page *page, unsigned pg_len)
{
struct request_queue *q;
struct ore_per_dev_state *per_dev;
@@ -366,17 +366,60 @@ static int _add_to_read_4_write(struct o
_ore_add_sg_seg(per_dev, gap, true);
}
q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
- added_len = bio_add_pc_page(q, per_dev->bio, page, PAGE_SIZE, 0);
- if (unlikely(added_len != PAGE_SIZE)) {
+ added_len = bio_add_pc_page(q, per_dev->bio, page, pg_len,
+ si->obj_offset % PAGE_SIZE);
+ if (unlikely(added_len != pg_len)) {
ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
per_dev->bio->bi_vcnt);
return -ENOMEM;
}

- per_dev->length += PAGE_SIZE;
+ per_dev->length += pg_len;
return 0;
}

+/* read the beginning of an unaligned first page */
+static int _add_to_r4w_first_page(struct ore_io_state *ios, struct page *page)
+{
+ struct ore_striping_info si;
+ unsigned pg_len;
+
+ ore_calc_stripe_info(ios->layout, ios->offset, 0, &si);
+
+ pg_len = si.obj_offset % PAGE_SIZE;
+ si.obj_offset -= pg_len;
+
+ ORE_DBGMSG("offset=0x%llx len=0x%x index=0x%lx dev=%x\n",
+ _LLU(si.obj_offset), pg_len, page->index, si.dev);
+
+ return _add_to_r4w(ios, &si, page, pg_len);
+}
+
+/* read the end of an incomplete last page */
+static int _add_to_r4w_last_page(struct ore_io_state *ios, u64 *offset)
+{
+ struct ore_striping_info si;
+ struct page *page;
+ unsigned pg_len, p, c;
+
+ ore_calc_stripe_info(ios->layout, *offset, 0, &si);
+
+ p = si.unit_off / PAGE_SIZE;
+ c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
+ ios->layout->mirrors_p1, si.par_dev, si.dev);
+ page = ios->sp2d->_1p_stripes[p].pages[c];
+
+ pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
+ *offset += pg_len;
+
+ ORE_DBGMSG("p=%d, c=%d next-offset=0x%llx len=0x%x dev=%x par_dev=%d\n",
+ p, c, _LLU(*offset), pg_len, si.dev, si.par_dev);
+
+ BUG_ON(!page);
+
+ return _add_to_r4w(ios, &si, page, pg_len);
+}
+
static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
{
struct bio_vec *bv;
@@ -444,9 +487,13 @@ static int _read_4_write(struct ore_io_s
struct page **pp = &_1ps->pages[c];
bool uptodate;

- if (*pp)
+ if (*pp) {
+ if (ios->offset % PAGE_SIZE)
+ /* Read the remainder of the page */
+ _add_to_r4w_first_page(ios, *pp);
/* to-be-written pages start here */
goto read_last_stripe;
+ }

*pp = ios->r4w->get_page(ios->private, offset,
&uptodate);
@@ -454,7 +501,7 @@ static int _read_4_write(struct ore_io_s
return -ENOMEM;

if (!uptodate)
- _add_to_read_4_write(ios, &read_si, *pp);
+ _add_to_r4w(ios, &read_si, *pp, PAGE_SIZE);

/* Mark read-pages to be cache_released */
_1ps->page_is_read[c] = true;
@@ -465,8 +512,11 @@ static int _read_4_write(struct ore_io_s
}

read_last_stripe:
- offset = ios->offset + (ios->length + PAGE_SIZE - 1) /
- PAGE_SIZE * PAGE_SIZE;
+ offset = ios->offset + ios->length;
+ if (offset % PAGE_SIZE)
+ _add_to_r4w_last_page(ios, &offset);
+ /* offset will be aligned to next page */
+
last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
* bytes_in_stripe;
if (offset == last_stripe_end) /* Optimize for the aligned case */
@@ -503,7 +553,7 @@ read_last_stripe:
/* Mark read-pages to be cache_released */
_1ps->page_is_read[c] = true;
if (!uptodate)
- _add_to_read_4_write(ios, &read_si, page);
+ _add_to_r4w(ios, &read_si, page, PAGE_SIZE);
}

offset += PAGE_SIZE;
@@ -616,8 +666,6 @@ int _ore_post_alloc_raid_stuff(struct or
return -ENOMEM;
}

- BUG_ON(ios->offset % PAGE_SIZE);
-
/* Round io down to last full strip */
first_stripe = div_u64(ios->offset, stripe_size);
last_stripe = div_u64(ios->offset + ios->length, stripe_size);



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