[merged mm-nonmm-stable] hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: hfsplus: convert kmap() to kmap_local_page() in bitmap.c
has been removed from the -mm tree.  Its filename was
     hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch

This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: hfsplus: convert kmap() to kmap_local_page() in bitmap.c
Date: Tue, 9 Aug 2022 22:31:04 +0200

kmap() is being deprecated in favor of kmap_local_page().

There are two main problems with kmap(): (1) It comes with an overhead as
mapping space is restricted and protected by a global lock for
synchronization and (2) it also requires global TLB invalidation when the
kmap's pool wraps and it might block when the mapping space is fully
utilized until a slot becomes available.

With kmap_local_page() the mappings are per thread, CPU local, can take
page faults, and can be called from any context (including interrupts). 
It is faster than kmap() in kernels with HIGHMEM enabled.  Furthermore,
the tasks can be preempted and, when they are scheduled to run again, the
kernel virtual addresses are restored and are still valid.

Since its use in bitmap.c is safe everywhere, it should be preferred.

Therefore, replace kmap() with kmap_local_page() in bitmap.c.

Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
HIGHMEM64GB enabled.

Link: https://lkml.kernel.org/r/20220809203105.26183-4-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/hfsplus/bitmap.c |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/fs/hfsplus/bitmap.c~hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc
+++ a/fs/hfsplus/bitmap.c
@@ -39,7 +39,7 @@ int hfsplus_block_allocate(struct super_
 		start = size;
 		goto out;
 	}
-	pptr = kmap(page);
+	pptr = kmap_local_page(page);
 	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
 	i = offset % 32;
 	offset &= ~(PAGE_CACHE_BITS - 1);
@@ -74,7 +74,7 @@ int hfsplus_block_allocate(struct super_
 			}
 			curr++;
 		}
-		kunmap(page);
+		kunmap_local(pptr);
 		offset += PAGE_CACHE_BITS;
 		if (offset >= size)
 			break;
@@ -84,7 +84,7 @@ int hfsplus_block_allocate(struct super_
 			start = size;
 			goto out;
 		}
-		curr = pptr = kmap(page);
+		curr = pptr = kmap_local_page(page);
 		if ((size ^ offset) / PAGE_CACHE_BITS)
 			end = pptr + PAGE_CACHE_BITS / 32;
 		else
@@ -127,7 +127,7 @@ found:
 			len -= 32;
 		}
 		set_page_dirty(page);
-		kunmap(page);
+		kunmap_local(pptr);
 		offset += PAGE_CACHE_BITS;
 		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
 					 NULL);
@@ -135,7 +135,7 @@ found:
 			start = size;
 			goto out;
 		}
-		pptr = kmap(page);
+		pptr = kmap_local_page(page);
 		curr = pptr;
 		end = pptr + PAGE_CACHE_BITS / 32;
 	}
@@ -151,7 +151,7 @@ last:
 done:
 	*curr = cpu_to_be32(n);
 	set_page_dirty(page);
-	kunmap(page);
+	kunmap_local(pptr);
 	*max = offset + (curr - pptr) * 32 + i - start;
 	sbi->free_blocks -= *max;
 	hfsplus_mark_mdb_dirty(sb);
@@ -185,7 +185,7 @@ int hfsplus_block_free(struct super_bloc
 	page = read_mapping_page(mapping, pnr, NULL);
 	if (IS_ERR(page))
 		goto kaboom;
-	pptr = kmap(page);
+	pptr = kmap_local_page(page);
 	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
 	end = pptr + PAGE_CACHE_BITS / 32;
 	len = count;
@@ -215,11 +215,11 @@ int hfsplus_block_free(struct super_bloc
 		if (!count)
 			break;
 		set_page_dirty(page);
-		kunmap(page);
+		kunmap_local(pptr);
 		page = read_mapping_page(mapping, ++pnr, NULL);
 		if (IS_ERR(page))
 			goto kaboom;
-		pptr = kmap(page);
+		pptr = kmap_local_page(page);
 		curr = pptr;
 		end = pptr + PAGE_CACHE_BITS / 32;
 	}
@@ -231,7 +231,7 @@ done:
 	}
 out:
 	set_page_dirty(page);
-	kunmap(page);
+	kunmap_local(pptr);
 	sbi->free_blocks += len;
 	hfsplus_mark_mdb_dirty(sb);
 	mutex_unlock(&sbi->alloc_mutex);
_

Patches currently in -mm which might be from fmdefrancesco@gmail.com are