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From:   NeilBrown <neilb@suse.com>
To:     Oleg Drokin <oleg.drokin@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        James Simmons <jsimmons@infradead.org>,
        Andreas Dilger <andreas.dilger@intel.com>
Date:   Fri, 02 Mar 2018 10:31:25 +1100
Subject: [PATCH 02/17] staging: lustre: fix bug in osc_enter_cache_try
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lustre Development List <lustre-devel@lists.lustre.org>
Message-ID: <151994708510.7628.7308229784516417641.stgit@noble>
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The lustre-release patch commit bdc5bb52c554 ("LU-4933 osc:
Automatically increase the max_dirty_mb") changed

-       if (cli->cl_dirty + PAGE_CACHE_SIZE <= cli->cl_dirty_max &&
+       if (cli->cl_dirty_pages < cli->cl_dirty_max_pages &&

When this patch landed in Linux a couple of years later, it landed as

-       if (cli->cl_dirty + PAGE_SIZE <= cli->cl_dirty_max &&
+       if (cli->cl_dirty_pages <= cli->cl_dirty_max_pages &&

which is clearly different ('<=' vs '<'), and allows cl_dirty_pages to
increase beyond cl_dirty_max_pages - which causes a latter assertion
to fails.

Fixes: 3147b268400a ("staging: lustre: osc: Automatically increase the max_dirty_mb")
Signed-off-by: NeilBrown <neilb@suse.com>
---
 drivers/staging/lustre/lustre/include/obd.h   |    2 +-
 drivers/staging/lustre/lustre/osc/osc_cache.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lustre/include/obd.h b/drivers/staging/lustre/lustre/include/obd.h
index 4368f4e9f208..f1233ca7d337 100644
--- a/drivers/staging/lustre/lustre/include/obd.h
+++ b/drivers/staging/lustre/lustre/include/obd.h
@@ -191,7 +191,7 @@ struct client_obd {
 	struct sptlrpc_flavor    cl_flvr_mgc;   /* fixed flavor of mgc->mgs */
 
 	/* the grant values are protected by loi_list_lock below */
-	unsigned long		 cl_dirty_pages;	/* all _dirty_ in pahges */
+	unsigned long		 cl_dirty_pages;	/* all _dirty_ in pages */
 	unsigned long		 cl_dirty_max_pages;	/* allowed w/o rpc */
 	unsigned long		 cl_dirty_transit;	/* dirty synchronous */
 	unsigned long		 cl_avail_grant;	/* bytes of credit for ost */
diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
index 1c70a504ee89..459503727ce3 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cache.c
+++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
@@ -1529,7 +1529,7 @@ static int osc_enter_cache_try(struct client_obd *cli,
 	if (rc < 0)
 		return 0;
 
-	if (cli->cl_dirty_pages <= cli->cl_dirty_max_pages &&
+	if (cli->cl_dirty_pages < cli->cl_dirty_max_pages &&
 	    atomic_long_read(&obd_dirty_pages) + 1 <= obd_max_dirty_pages) {
 		osc_consume_write_grant(cli, &oap->oap_brw_page);
 		if (transient) {