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Date: Sat, 28 Jan 2017 19:05:00 -0500
From: James Simmons <jsimmons@...radead.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
devel@...verdev.osuosl.org,
Andreas Dilger <andreas.dilger@...el.com>,
Oleg Drokin <oleg.drokin@...el.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lustre Development List <lustre-devel@...ts.lustre.org>,
Jinshan Xiong <jinshan.xiong@...el.com>,
Dmitry Eremin <dmitry.eremin@...el.com>,
James Simmons <jsimmons@...radead.org>
Subject: [PATCH 32/60] staging: lustre: osc: limits the number of chunks in write RPC
From: Jinshan Xiong <jinshan.xiong@...el.com>
OSC has to make sure that it won't issue write RPCs with too many
chunks otherwise it will casue ZFS to create transactions much
bigger than DMU_MAX_ACCESS in size, which will end up with write
failure.
Signed-off-by: Jinshan Xiong <jinshan.xiong@...el.com>
Signed-off-by: Dmitry Eremin <dmitry.eremin@...el.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8135
Reviewed-on: http://review.whamcloud.com/22369
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8632
Reviewed-on: http://review.whamcloud.com/22654
Reviewed-by: Andreas Dilger <andreas.dilger@...el.com>
Reviewed-by: Patrick Farrell <paf@...y.com>
Reviewed-by: Oleg Drokin <oleg.drokin@...el.com>
Signed-off-by: James Simmons <jsimmons@...radead.org>
---
drivers/staging/lustre/lustre/osc/osc_cache.c | 124 ++++++++++++++++++--------
1 file changed, 87 insertions(+), 37 deletions(-)
diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
index 72dd554..0490478 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cache.c
+++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
@@ -1882,16 +1882,32 @@ static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
oap, osc, rc);
}
+struct extent_rpc_data {
+ struct list_head *erd_rpc_list;
+ unsigned int erd_page_count;
+ unsigned int erd_max_pages;
+ unsigned int erd_max_chunks;
+};
+
+static inline unsigned osc_extent_chunks(const struct osc_extent *ext)
+{
+ struct client_obd *cli = osc_cli(ext->oe_obj);
+ unsigned ppc_bits = cli->cl_chunkbits - PAGE_SHIFT;
+
+ return (ext->oe_end >> ppc_bits) - (ext->oe_start >> ppc_bits) + 1;
+}
+
/**
* Try to add extent to one RPC. We need to think about the following things:
* - # of pages must not be over max_pages_per_rpc
* - extent must be compatible with previous ones
*/
static int try_to_add_extent_for_io(struct client_obd *cli,
- struct osc_extent *ext, struct list_head *rpclist,
- unsigned int *pc, unsigned int *max_pages)
+ struct osc_extent *ext,
+ struct extent_rpc_data *data)
{
struct osc_extent *tmp;
+ unsigned int chunk_count;
struct osc_async_page *oap = list_first_entry(&ext->oe_pages,
struct osc_async_page,
oap_pending_item);
@@ -1899,19 +1915,22 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
EASSERT((ext->oe_state == OES_CACHE || ext->oe_state == OES_LOCK_DONE),
ext);
- *max_pages = max(ext->oe_mppr, *max_pages);
- if (*pc + ext->oe_nr_pages > *max_pages)
+ chunk_count = osc_extent_chunks(ext);
+ if (chunk_count > data->erd_max_chunks)
+ return 0;
+
+ data->erd_max_pages = max(ext->oe_mppr, data->erd_max_pages);
+ if (data->erd_page_count + ext->oe_nr_pages > data->erd_max_pages)
return 0;
- list_for_each_entry(tmp, rpclist, oe_link) {
+ list_for_each_entry(tmp, data->erd_rpc_list, oe_link) {
struct osc_async_page *oap2;
oap2 = list_first_entry(&tmp->oe_pages, struct osc_async_page,
oap_pending_item);
EASSERT(tmp->oe_owner == current, tmp);
if (oap2cl_page(oap)->cp_type != oap2cl_page(oap2)->cp_type) {
- CDEBUG(D_CACHE, "Do not permit different type of IO"
- " for a same RPC\n");
+ CDEBUG(D_CACHE, "Do not permit different type of IO in one RPC\n");
return 0;
}
@@ -1924,12 +1943,41 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
break;
}
- *pc += ext->oe_nr_pages;
- list_move_tail(&ext->oe_link, rpclist);
+ data->erd_max_chunks -= chunk_count;
+ data->erd_page_count += ext->oe_nr_pages;
+ list_move_tail(&ext->oe_link, data->erd_rpc_list);
ext->oe_owner = current;
return 1;
}
+static inline unsigned osc_max_write_chunks(const struct client_obd *cli)
+{
+ /*
+ * LU-8135:
+ *
+ * The maximum size of a single transaction is about 64MB in ZFS.
+ * #define DMU_MAX_ACCESS (64 * 1024 * 1024)
+ *
+ * Since ZFS is a copy-on-write file system, a single dirty page in
+ * a chunk will result in the rewrite of the whole chunk, therefore
+ * an RPC shouldn't be allowed to contain too many chunks otherwise
+ * it will make transaction size much bigger than 64MB, especially
+ * with big block size for ZFS.
+ *
+ * This piece of code is to make sure that OSC won't send write RPCs
+ * with too many chunks. The maximum chunk size that an RPC can cover
+ * is set to PTLRPC_MAX_BRW_SIZE, which is defined to 16MB. Ideally
+ * OST should tell the client what the biggest transaction size is,
+ * but it's good enough for now.
+ *
+ * This limitation doesn't apply to ldiskfs, which allows as many
+ * chunks in one RPC as we want. However, it won't have any benefits
+ * to have too many discontiguous pages in one RPC. Therefore, it
+ * can only have 256 chunks at most in one RPC.
+ */
+ return min(PTLRPC_MAX_BRW_SIZE >> cli->cl_chunkbits, 256);
+}
+
/**
* In order to prevent multiple ptlrpcd from breaking contiguous extents,
* get_write_extent() takes all appropriate extents in atomic.
@@ -1949,26 +1997,28 @@ static unsigned int get_write_extents(struct osc_object *obj,
struct client_obd *cli = osc_cli(obj);
struct osc_extent *ext;
struct osc_extent *temp;
- unsigned int page_count = 0;
- unsigned int max_pages = cli->cl_max_pages_per_rpc;
+ struct extent_rpc_data data = {
+ .erd_rpc_list = rpclist,
+ .erd_page_count = 0,
+ .erd_max_pages = cli->cl_max_pages_per_rpc,
+ .erd_max_chunks = osc_max_write_chunks(cli),
+ };
LASSERT(osc_object_is_locked(obj));
list_for_each_entry_safe(ext, temp, &obj->oo_hp_exts, oe_link) {
LASSERT(ext->oe_state == OES_CACHE);
- if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
- &max_pages))
- return page_count;
- EASSERT(ext->oe_nr_pages <= max_pages, ext);
+ if (!try_to_add_extent_for_io(cli, ext, &data))
+ return data.erd_page_count;
+ EASSERT(ext->oe_nr_pages <= data.erd_max_pages, ext);
}
- if (page_count == max_pages)
- return page_count;
+ if (data.erd_page_count == data.erd_max_pages)
+ return data.erd_page_count;
while (!list_empty(&obj->oo_urgent_exts)) {
ext = list_entry(obj->oo_urgent_exts.next,
struct osc_extent, oe_link);
- if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
- &max_pages))
- return page_count;
+ if (!try_to_add_extent_for_io(cli, ext, &data))
+ return data.erd_page_count;
if (!ext->oe_intree)
continue;
@@ -1979,13 +2029,12 @@ static unsigned int get_write_extents(struct osc_object *obj,
ext->oe_owner))
continue;
- if (!try_to_add_extent_for_io(cli, ext, rpclist,
- &page_count, &max_pages))
- return page_count;
+ if (!try_to_add_extent_for_io(cli, ext, &data))
+ return data.erd_page_count;
}
}
- if (page_count == max_pages)
- return page_count;
+ if (data.erd_page_count == data.erd_max_pages)
+ return data.erd_page_count;
ext = first_extent(obj);
while (ext) {
@@ -1996,13 +2045,12 @@ static unsigned int get_write_extents(struct osc_object *obj,
continue;
}
- if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
- &max_pages))
- return page_count;
+ if (!try_to_add_extent_for_io(cli, ext, &data))
+ return data.erd_page_count;
ext = next_extent(ext);
}
- return page_count;
+ return data.erd_page_count;
}
static int
@@ -2087,27 +2135,29 @@ static unsigned int get_write_extents(struct osc_object *obj,
struct osc_extent *ext;
struct osc_extent *next;
LIST_HEAD(rpclist);
- unsigned int page_count = 0;
- unsigned int max_pages = cli->cl_max_pages_per_rpc;
+ struct extent_rpc_data data = {
+ .erd_rpc_list = &rpclist,
+ .erd_page_count = 0,
+ .erd_max_pages = cli->cl_max_pages_per_rpc,
+ .erd_max_chunks = UINT_MAX,
+ };
int rc = 0;
LASSERT(osc_object_is_locked(osc));
list_for_each_entry_safe(ext, next, &osc->oo_reading_exts, oe_link) {
EASSERT(ext->oe_state == OES_LOCK_DONE, ext);
- if (!try_to_add_extent_for_io(cli, ext, &rpclist, &page_count,
- &max_pages))
+ if (!try_to_add_extent_for_io(cli, ext, &data))
break;
osc_extent_state_set(ext, OES_RPC);
- EASSERT(ext->oe_nr_pages <= max_pages, ext);
+ EASSERT(ext->oe_nr_pages <= data.erd_max_pages, ext);
}
- LASSERT(page_count <= max_pages);
+ LASSERT(data.erd_page_count <= data.erd_max_pages);
- osc_update_pending(osc, OBD_BRW_READ, -page_count);
+ osc_update_pending(osc, OBD_BRW_READ, -data.erd_page_count);
if (!list_empty(&rpclist)) {
osc_object_unlock(osc);
- LASSERT(page_count > 0);
rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ);
LASSERT(list_empty(&rpclist));
--
1.8.3.1
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