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File 79f03c2.diff of Package openafs (Revision e8a6721c3209c185cb0f018ef461da64)

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From 79f03c2d6714e653cee4aa6af81d6568ad4368b7 Mon Sep 17 00:00:00 2001
From: Cheyenne Wills <cwills@sinenomine.net>
Date: Thu, 22 Sep 2022 13:04:59 -0600
Subject: [PATCH] Linux-6.0: Replace add_to_page_cache

Linux 6.0 removed the add_to_page_cache function in the Linux commit:
    'filemap: Remove add_to_page_cache() and add_to_page_cache_locked()'
    (2bb876b58d593d7f2522ec0f41f20a74fde76822)

The replacement function, filemap_add_folio function is exported as GPL,
but a non-GPL wrapper was provided in the Linux 5.15 commit:
    'mm/filemap: Add filemap_add_folio()'
    (9dd3d069406cea073fc633e77bc59abbfde8c6c4)
which changed the GPL exported function add_to_page_cache_lru to a
non-GPL exported function.

The function add_to_page_cache_lru functionally combines the
add_to_page_cache with lru_cache_add.  Within afs, all the calls to
add_to_page_cache follow the pattern of calling the lru_cache_add
via the wrapper afs_lru_cache_add immediately after (except in one case
noted below).

Add an autoconf check to see if add_to_page_cache_lru is available.

Introduce a new wrapper function afs_add_to_page_cache_lru that handles
calling either add_to_page_cache/afs_lru_cache_add or
add_to_page_cache_lru.

As noted above there is one function, afs_linux_bypass_readpages, that
calls add_to_page_cache but does not immediately call afs_lru_cache_add.
This function is only used in Linux kernels prior to 5.18, see the
commit:
    'Linux-5.18: replace readpages with readahead' (7a181415db)
Since this code path is only built for a Linux kernel level where
add_to_page_cache should also exists, we do not replace this call.

NOTE:
The add_to_page_cache_lru was moved into mm/folio-compat.c which has a
comment indicating that callers of these functions should migrate to
folio calls.  However the replacement folio call that is needed by afs,
filemap_add_folio, is exported as GPL.

Reviewed-on: https://gerrit.openafs.org/15132
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 0ce315f0cee1cff7e19e6ebcc0e0e82e03719c20)

Change-Id: Ic0496c2fba00e7be467dbbcf52d9854495e1ad9f
---

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 621e4da..bec30bb 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -148,6 +148,23 @@
 }
 #endif /* !HAVE_LINUX_LRU_ADD_FILE */
 
+static inline int
+afs_add_to_page_cache_lru(struct afs_lru_pages *alrupages, struct page *page,
+			  struct address_space *mapping,
+			  pgoff_t index, gfp_t gfp)
+{
+#if defined(HAVE_LINUX_ADD_TO_PAGE_CACHE_LRU)
+    return add_to_page_cache_lru(page, mapping, index, gfp);
+#else
+    int code;
+    code = add_to_page_cache(page, mapping, index, gfp);
+    if (code == 0) {
+	afs_lru_cache_add(alrupages, page);
+    }
+    return code;
+#endif
+}
+
 /* This function converts a positive error code from AFS into a negative
  * code suitable for passing into the Linux VFS layer. It checks that the
  * error code is within the permissable bounds for the ERR_PTR mechanism.
@@ -2269,12 +2286,11 @@
 		goto out;
 	    }
 
-	    code = add_to_page_cache(newpage, cachemapping,
-				     pageindex, GFP_KERNEL);
+	    code = afs_add_to_page_cache_lru(alrupages, newpage, cachemapping,
+					     pageindex, GFP_KERNEL);
 	    if (code == 0) {
 	        cachepage = newpage;
 	        newpage = NULL;
-		afs_lru_cache_add(alrupages, cachepage);
 	    } else {
 		put_page(newpage);
 		newpage = NULL;
@@ -3092,11 +3108,9 @@
 	    goto out;
 	}
 
-	if (tdc && !add_to_page_cache(page, mapping, page->index,
-				      GFP_KERNEL)) {
-	    afs_lru_cache_add(&lrupages, page);
-
-	    /* Note that add_to_page_cache() locked 'page'.
+	if (tdc && !afs_add_to_page_cache_lru(&lrupages, page, mapping, page->index,
+					      GFP_KERNEL)) {
+	    /* Note that afs_add_to_page_cache_lru() locks the 'page'.
 	     * afs_linux_read_cache() is guaranteed to handle unlocking it. */
 	    afs_linux_read_cache(cacheFp, page, tdc->f.chunk, &lrupages, task);
 	}
diff --git a/src/cf/linux-kernel-func.m4 b/src/cf/linux-kernel-func.m4
index 27a1d41..d3abdf9 100644
--- a/src/cf/linux-kernel-func.m4
+++ b/src/cf/linux-kernel-func.m4
@@ -189,6 +189,16 @@
                      #include <linux/kthread.h>],
                     [kthread_complete_and_exit(0, 0);])
 
+dnl Linux 6.0 removed add_to_page_cache.  It's replacement, filemap_add_folio,
+dnl was added in 5.15 and is GPL-only, but has a NON-GPL wrapper called
+dnl add_to_page_cache_lru.
+dnl Note prior to 5.15, add_to_page_cache_lru was either not exported or
+dnl or exported as GPL-only.
+AC_CHECK_LINUX_FUNC([add_to_page_cache_lru],
+                    [#include <linux/kernel.h>
+                     #include <linux/pagemap.h>],
+                    [add_to_page_cache_lru(NULL, NULL, 0, 0);])
+
 dnl Consequences - things which get set as a result of the
 dnl                above tests
 AS_IF([test "x$ac_cv_linux_func_d_alloc_anon" = "xno"],

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