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Subject[PATCH 01/20] staging: lustre: osc: soft lock - osc_makes_rpc()
Date
From: Bobi Jam <bobijam.xu@intel.com>

It is possible that an osc_extent contains more than 256 chunks, and
the IO engine won't add this extent in one RPC
(try_to_add_extent_for_io) so that osc_check_rpcs() run into a loop
upon this extent and never break.

This patch changes osc_max_write_chunks() to make sure the value
can cover all possible osc_extent, so that all osc_extent will be
added into one RPC.

This patch also add another field erd_max_extents in extent_rpc_data
to make sure not to add too many fragments in a single RPC.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8680
Reviewed-on: http://review.whamcloud.com/23326
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
---
drivers/staging/lustre/lustre/osc/osc_cache.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
index d8a95f8..0100d27 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cache.c
+++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
@@ -1887,6 +1887,7 @@ struct extent_rpc_data {
unsigned int erd_page_count;
unsigned int erd_max_pages;
unsigned int erd_max_chunks;
+ unsigned int erd_max_extents;
};

static inline unsigned int osc_extent_chunks(const struct osc_extent *ext)
@@ -1915,11 +1916,23 @@ 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);

+ if (!data->erd_max_extents)
+ return 0;
+
chunk_count = osc_extent_chunks(ext);
+ EASSERTF(data->erd_page_count != 0 ||
+ chunk_count <= data->erd_max_chunks, ext,
+ "The first extent to be fit in a RPC contains %u chunks, which is over the limit %u.\n",
+ chunk_count, data->erd_max_chunks);
+
if (chunk_count > data->erd_max_chunks)
return 0;

data->erd_max_pages = max(ext->oe_mppr, data->erd_max_pages);
+ EASSERTF(data->erd_page_count != 0 ||
+ ext->oe_nr_pages <= data->erd_max_pages, ext,
+ "The first extent to be fit in a RPC contains %u pages, which is over the limit %u.\n",
+ ext->oe_nr_pages, data->erd_max_pages);
if (data->erd_page_count + ext->oe_nr_pages > data->erd_max_pages)
return 0;

@@ -1943,6 +1956,7 @@ static int try_to_add_extent_for_io(struct client_obd *cli,
break;
}

+ data->erd_max_extents--;
data->erd_max_chunks -= chunk_count;
data->erd_page_count += ext->oe_nr_pages;
list_move_tail(&ext->oe_link, data->erd_rpc_list);
@@ -1972,10 +1986,12 @@ static inline unsigned int osc_max_write_chunks(const struct client_obd *cli)
*
* 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.
+ * to have too many discontiguous pages in one RPC.
+ *
+ * An osc_extent won't cover over a RPC size, so the chunks in an
+ * osc_extent won't bigger than PTLRPC_MAX_BRW_SIZE >> chunkbits.
*/
- return min(PTLRPC_MAX_BRW_SIZE >> cli->cl_chunkbits, 256);
+ return PTLRPC_MAX_BRW_SIZE >> cli->cl_chunkbits;
}

/**
@@ -2002,6 +2018,7 @@ static unsigned int get_write_extents(struct osc_object *obj,
.erd_page_count = 0,
.erd_max_pages = cli->cl_max_pages_per_rpc,
.erd_max_chunks = osc_max_write_chunks(cli),
+ .erd_max_extents = 256,
};

LASSERT(osc_object_is_locked(obj));
@@ -2140,6 +2157,7 @@ static unsigned int get_write_extents(struct osc_object *obj,
.erd_page_count = 0,
.erd_max_pages = cli->cl_max_pages_per_rpc,
.erd_max_chunks = UINT_MAX,
+ .erd_max_extents = UINT_MAX,
};
int rc = 0;

--
1.8.3.1
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