[RFC PATCH v1 09/57] fs/nfs: Remove PAGE_SIZE compile-time constant assumption

[Ryan Roberts <ryan.roberts@arm.com>]

To prepare for supporting boot-time page size selection, refactor code
to remove assumptions about PAGE_SIZE being compile-time constant. Code
intended to be equivalent when compile-time page size is active.

Calculation of NFS4ACL_MAXPAGES and NFS4XATTR_MAXPAGES are modified to
give max pages when page size is at the minimum.

BUILD_BUG_ON() is modified to test against the min page size, which
implicitly also applies to all other page sizes.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---

***NOTE***
Any confused maintainers may want to read the cover note here for context:
https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/

 fs/nfs/nfs42proc.c  | 2 +-
 fs/nfs/nfs42xattr.c | 2 +-
 fs/nfs/nfs4proc.c   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index 28704f924612c..c600574105c63 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -1161,7 +1161,7 @@ int nfs42_proc_clone(struct file *src_f, struct file *dst_f,
 	return err;
 }
 
-#define NFS4XATTR_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE)
+#define NFS4XATTR_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE_MIN)
 
 static int _nfs42_proc_removexattr(struct inode *inode, const char *name)
 {
diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
index b6e3d8f77b910..734177eb44889 100644
--- a/fs/nfs/nfs42xattr.c
+++ b/fs/nfs/nfs42xattr.c
@@ -183,7 +183,7 @@ nfs4_xattr_alloc_entry(const char *name, const void *value,
 	uint32_t flags;
 
 	BUILD_BUG_ON(sizeof(struct nfs4_xattr_entry) +
-	    XATTR_NAME_MAX + 1 > PAGE_SIZE);
+	    XATTR_NAME_MAX + 1 > PAGE_SIZE_MIN);
 
 	alloclen = sizeof(struct nfs4_xattr_entry);
 	if (name != NULL) {
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b8ffbe52ba15a..3c3622f46d3e0 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5928,7 +5928,7 @@ static bool nfs4_server_supports_acls(const struct nfs_server *server,
  * it's OK to put sizeof(void) * (XATTR_SIZE_MAX/PAGE_SIZE) bytes on
  * the stack.
  */
-#define NFS4ACL_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE)
+#define NFS4ACL_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE_MIN)
 
 int nfs4_buf_to_pages_noslab(const void *buf, size_t buflen,
 		struct page **pages)
-- 
2.43.0