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From ea74bb05c9a36bcf77698008d340202959be8091 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.
Change-Id: I10087ebeb8b08309e6c1bab4fc43f7e9f50bd105
---
src/afs/LINUX/osi_vnodeops.c | 30 ++++++++++++++++++++++--------
src/cf/linux-kernel-func.m4 | 10 ++++++++++
2 files changed, 32 insertions(+), 8 deletions(-)
diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 621e4da38..bec30bb4c 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -148,6 +148,23 @@ afs_lru_cache_finalize(struct afs_lru_pages *alrupages)
}
#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 @@ afs_linux_read_cache(struct file *cachefp, struct page *page,
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 @@ afs_linux_readpages(struct file *fp, struct address_space *mapping,
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 27a1d4141..d3abdf9ff 100644
--- a/src/cf/linux-kernel-func.m4
+++ b/src/cf/linux-kernel-func.m4
@@ -189,6 +189,16 @@ AC_CHECK_LINUX_FUNC([kthread_complete_and_exit],
#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"],
--
2.37.3
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