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authorBoaz Harrosh <bharrosh@panasas.com>2012-06-08 02:19:07 +0400
committerBoaz Harrosh <bharrosh@panasas.com>2012-07-20 12:45:28 +0400
commit9ff19309a9623f2963ac5a136782ea4d8b5d67fb (patch)
tree3d91d486964cbae927a3ac8795679961f4200f8c /fs/exofs/ore_raid.c
parent6887a4131da3adaab011613776d865f4bcfb5678 (diff)
downloadlinux-9ff19309a9623f2963ac5a136782ea4d8b5d67fb.tar.xz
ore: Fix NFS crash by supporting any unaligned RAID IO
In RAID_5/6 We used to not permit an IO that it's end byte is not stripe_size aligned and spans more than one stripe. .i.e the caller must check if after submission the actual transferred bytes is shorter, and would need to resubmit a new IO with the remainder. Exofs supports this, and NFS was supposed to support this as well with it's short write mechanism. But late testing has exposed a CRASH when this is used with none-RPC layout-drivers. The change at NFS is deep and risky, in it's place the fix at ORE to lift the limitation is actually clean and simple. So here it is below. The principal here is that in the case of unaligned IO on both ends, beginning and end, we will send two read requests one like old code, before the calculation of the first stripe, and also a new site, before the calculation of the last stripe. If any "boundary" is aligned or the complete IO is within a single stripe. we do a single read like before. The code is clean and simple by splitting the old _read_4_write into 3 even parts: 1._read_4_write_first_stripe 2. _read_4_write_last_stripe 3. _read_4_write_execute And calling 1+3 at the same place as before. 2+3 before last stripe, and in the case of all in a single stripe then 1+2+3 is preformed additively. Why did I not think of it before. Well I had a strike of genius because I have stared at this code for 2 years, and did not find this simple solution, til today. Not that I did not try. This solution is much better for NFS than the previous supposedly solution because the short write was dealt with out-of-band after IO_done, which would cause for a seeky IO pattern where as in here we execute in order. At both solutions we do 2 separate reads, only here we do it within a single IO request. (And actually combine two writes into a single submission) NFS/exofs code need not change since the ORE API communicates the new shorter length on return, what will happen is that this case would not occur anymore. hurray!! [Stable this is an NFS bug since 3.2 Kernel should apply cleanly] CC: Stable Tree <stable@kernel.org> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Diffstat (limited to 'fs/exofs/ore_raid.c')
-rw-r--r--fs/exofs/ore_raid.c67
1 files changed, 36 insertions, 31 deletions
diff --git a/fs/exofs/ore_raid.c b/fs/exofs/ore_raid.c
index d222c77cfa1b..fff2070c6751 100644
--- a/fs/exofs/ore_raid.c
+++ b/fs/exofs/ore_raid.c
@@ -461,16 +461,12 @@ static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
* ios->sp2d[p][*], xor is calculated the same way. These pages are
* allocated/freed and don't go through cache
*/
-static int _read_4_write(struct ore_io_state *ios)
+static int _read_4_write_first_stripe(struct ore_io_state *ios)
{
- struct ore_io_state *ios_read;
struct ore_striping_info read_si;
struct __stripe_pages_2d *sp2d = ios->sp2d;
u64 offset = ios->si.first_stripe_start;
- u64 last_stripe_end;
- unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
- unsigned i, c, p, min_p = sp2d->pages_in_unit, max_p = -1;
- int ret;
+ unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
if (offset == ios->offset) /* Go to start collect $200 */
goto read_last_stripe;
@@ -478,6 +474,9 @@ static int _read_4_write(struct ore_io_state *ios)
min_p = _sp2d_min_pg(sp2d);
max_p = _sp2d_max_pg(sp2d);
+ ORE_DBGMSG("stripe_start=0x%llx ios->offset=0x%llx min_p=%d max_p=%d\n",
+ offset, ios->offset, min_p, max_p);
+
for (c = 0; ; c++) {
ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
read_si.obj_offset += min_p * PAGE_SIZE;
@@ -512,6 +511,18 @@ static int _read_4_write(struct ore_io_state *ios)
}
read_last_stripe:
+ return 0;
+}
+
+static int _read_4_write_last_stripe(struct ore_io_state *ios)
+{
+ struct ore_striping_info read_si;
+ struct __stripe_pages_2d *sp2d = ios->sp2d;
+ u64 offset;
+ u64 last_stripe_end;
+ unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
+ unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
+
offset = ios->offset + ios->length;
if (offset % PAGE_SIZE)
_add_to_r4w_last_page(ios, &offset);
@@ -527,15 +538,15 @@ read_last_stripe:
c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
ios->layout->mirrors_p1, read_si.par_dev, read_si.dev);
- BUG_ON(ios->si.first_stripe_start + bytes_in_stripe != last_stripe_end);
- /* unaligned IO must be within a single stripe */
-
if (min_p == sp2d->pages_in_unit) {
/* Didn't do it yet */
min_p = _sp2d_min_pg(sp2d);
max_p = _sp2d_max_pg(sp2d);
}
+ ORE_DBGMSG("offset=0x%llx stripe_end=0x%llx min_p=%d max_p=%d\n",
+ offset, last_stripe_end, min_p, max_p);
+
while (offset < last_stripe_end) {
struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
@@ -568,6 +579,15 @@ read_last_stripe:
}
read_it:
+ return 0;
+}
+
+static int _read_4_write_execute(struct ore_io_state *ios)
+{
+ struct ore_io_state *ios_read;
+ unsigned i;
+ int ret;
+
ios_read = ios->ios_read_4_write;
if (!ios_read)
return 0;
@@ -591,6 +611,8 @@ read_it:
}
_mark_read4write_pages_uptodate(ios_read, ret);
+ ore_put_io_state(ios_read);
+ ios->ios_read_4_write = NULL; /* Might need a reuse at last stripe */
return 0;
}
@@ -626,8 +648,11 @@ int _ore_add_parity_unit(struct ore_io_state *ios,
/* If first stripe, Read in all read4write pages
* (if needed) before we calculate the first parity.
*/
- _read_4_write(ios);
+ _read_4_write_first_stripe(ios);
}
+ if (!cur_len) /* If last stripe r4w pages of last stripe */
+ _read_4_write_last_stripe(ios);
+ _read_4_write_execute(ios);
for (i = 0; i < num_pages; i++) {
pages[i] = _raid_page_alloc();
@@ -654,34 +679,14 @@ int _ore_add_parity_unit(struct ore_io_state *ios,
int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
{
- struct ore_layout *layout = ios->layout;
-
if (ios->parity_pages) {
+ struct ore_layout *layout = ios->layout;
unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
- unsigned stripe_size = ios->si.bytes_in_stripe;
- u64 last_stripe, first_stripe;
if (_sp2d_alloc(pages_in_unit, layout->group_width,
layout->parity, &ios->sp2d)) {
return -ENOMEM;
}
-
- /* 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);
-
- /* If an IO spans more then a single stripe it must end at
- * a stripe boundary. The reminder at the end is pushed into the
- * next IO.
- */
- if (last_stripe != first_stripe) {
- ios->length = last_stripe * stripe_size - ios->offset;
-
- BUG_ON(!ios->length);
- ios->nr_pages = (ios->length + PAGE_SIZE - 1) /
- PAGE_SIZE;
- ios->si.length = ios->length; /*make it consistent */
- }
}
return 0;
}