LU-16671 osc: fix unstable pages for short IO

Unstable pages was written with theoretical support for
short IO (ie, no bulk, data-in-rpc, LU-1757), but since the
short IO code wasn't merged until years later, they were
probably never tested together.  And when you do, it
crashes.

In truth, short IO has no separate pages to be tracked,
which is why this is crashing.  This means that small write
RPCs won't be tracked in unstable pages, but that's a very
minor limitation and unlikely to cause trouble.  (and since
RPC allocations are not 'pages', they're just malloc'ed,
there's no good way to track them anyway)

Fixes: 70f092a ("LU-1757 brw: add short io osc/ost transfer.")
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I34b09f8324424c3ff0b0c09c86f01c938b643e37
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50451
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Qian Yingjin <qian@ddn.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/osc/osc_page.c b/lustre/osc/osc_page.c
index 1030956..4db1f27 100644 (file)
--- a/lustre/osc/osc_page.c
+++ b/lustre/osc/osc_page.c
@@ -892,7 +892,6 @@ void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
 #endif
 
 static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
-                                           struct osc_brw_async_args *aa,
                                            int factor)
 {
        int page_count;
@@ -900,18 +899,15 @@ static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
        int count = 0;
        int i;
 
-       if (desc != NULL) {
-               page_count = desc->bd_iov_count;
-       } else {
-               page_count = aa->aa_page_count;
-       }
+       ENTRY;
+
+       page_count = desc->bd_iov_count;
+
+       CDEBUG(D_PAGE, "%s %d unstable pages\n",
+              factor == 1 ? "adding" : "removing", page_count);
 
        for (i = 0; i < page_count; i++) {
-               void *pz;
-               if (desc)
-                       pz = page_zone(desc->bd_vec[i].bv_page);
-               else
-                       pz = page_zone(aa->aa_ppga[i]->bp_page);
+               void *pz = page_zone(desc->bd_vec[i].bv_page);
 
                if (likely(pz == zone)) {
                        ++count;
@@ -930,18 +926,18 @@ static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
        if (count > 0)
                mod_zone_page_state(zone, (enum zone_stat_item)NR_WRITEBACK,
                                    factor * count);
+
+       EXIT;
 }
 
-static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
-                                               struct osc_brw_async_args *aa)
+static inline void add_unstable_pages(struct ptlrpc_bulk_desc *desc)
 {
-       unstable_page_accounting(desc, aa, 1);
+       unstable_page_accounting(desc, 1);
 }
 
-static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
-                                               struct osc_brw_async_args *aa)
+static inline void dec_unstable_pages(struct ptlrpc_bulk_desc *desc)
 {
-       unstable_page_accounting(desc, aa, -1);
+       unstable_page_accounting(desc, -1);
 }
 
 /**
@@ -958,19 +954,21 @@ static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
 void osc_dec_unstable_pages(struct ptlrpc_request *req)
 {
        struct ptlrpc_bulk_desc *desc       = req->rq_bulk;
-       struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
        struct client_obd       *cli        = &req->rq_import->imp_obd->u.cli;
        int                      page_count;
        long                     unstable_count;
 
-       if (desc)
-               page_count = desc->bd_iov_count;
-       else
-               page_count = aa->aa_page_count;
+       /* no desc means short io, which doesn't have separate unstable pages,
+        * it's just using space inside the RPC itself
+        */
+       if (!desc)
+               return;
+
+       page_count = desc->bd_iov_count;
 
        LASSERT(page_count >= 0);
 
-       dec_unstable_page_accounting(desc, aa);
+       dec_unstable_pages(desc);
 
        unstable_count = atomic_long_sub_return(page_count,
                                                &cli->cl_unstable_count);
@@ -992,7 +990,6 @@ void osc_dec_unstable_pages(struct ptlrpc_request *req)
 void osc_inc_unstable_pages(struct ptlrpc_request *req)
 {
        struct ptlrpc_bulk_desc *desc = req->rq_bulk;
-       struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
        struct client_obd       *cli  = &req->rq_import->imp_obd->u.cli;
        long                     page_count;
 
@@ -1000,12 +997,15 @@ void osc_inc_unstable_pages(struct ptlrpc_request *req)
        if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
                return;
 
-       if (desc)
-               page_count = desc->bd_iov_count;
-       else
-               page_count = aa->aa_page_count;
+       /* no desc means short io, which doesn't have separate unstable pages,
+        * it's just using space inside the RPC itself
+        */
+       if (!desc)
+               return;
+
+       page_count = desc->bd_iov_count;
 
-       add_unstable_page_accounting(desc, aa);
+       add_unstable_pages(desc);
        atomic_long_add(page_count, &cli->cl_unstable_count);
        atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);