The quilt patch titled
Subject: hfsplus: convert kmap() to kmap_local_page() in btree.c
has been removed from the -mm tree. Its filename was
hfsplus-convert-kmap-to-kmap_local_page-in-btreec.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@xxxxxxxxx>
Subject: hfsplus: convert kmap() to kmap_local_page() in btree.c
Date: Tue, 9 Aug 2022 22:31:05 +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 btree.c is safe everywhere, it should be preferred.
Therefore, replace kmap() with kmap_local_page() in btree.c.
Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
HIGHMEM64GB enabled.
Link: https://lkml.kernel.org/r/20220809203105.26183-5-fmdefrancesco@xxxxxxxxx
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
Suggested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Viacheslav Dubeyko <slava@xxxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hfsplus/btree.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
--- a/fs/hfsplus/btree.c~hfsplus-convert-kmap-to-kmap_local_page-in-btreec
+++ a/fs/hfsplus/btree.c
@@ -163,7 +163,7 @@ struct hfs_btree *hfs_btree_open(struct
goto free_inode;
/* Load the header */
- head = (struct hfs_btree_header_rec *)(kmap(page) +
+ head = (struct hfs_btree_header_rec *)(kmap_local_page(page) +
sizeof(struct hfs_bnode_desc));
tree->root = be32_to_cpu(head->root);
tree->leaf_count = be32_to_cpu(head->leaf_count);
@@ -240,12 +240,12 @@ struct hfs_btree *hfs_btree_open(struct
(tree->node_size + PAGE_SIZE - 1) >>
PAGE_SHIFT;
- kunmap(page);
+ kunmap_local(head);
put_page(page);
return tree;
fail_page:
- kunmap(page);
+ kunmap_local(head);
put_page(page);
free_inode:
tree->inode->i_mapping->a_ops = &hfsplus_aops;
@@ -292,7 +292,7 @@ int hfs_btree_write(struct hfs_btree *tr
return -EIO;
/* Load the header */
page = node->page[0];
- head = (struct hfs_btree_header_rec *)(kmap(page) +
+ head = (struct hfs_btree_header_rec *)(kmap_local_page(page) +
sizeof(struct hfs_bnode_desc));
head->root = cpu_to_be32(tree->root);
@@ -304,7 +304,7 @@ int hfs_btree_write(struct hfs_btree *tr
head->attributes = cpu_to_be32(tree->attributes);
head->depth = cpu_to_be16(tree->depth);
- kunmap(page);
+ kunmap_local(head);
set_page_dirty(page);
hfs_bnode_put(node);
return 0;
@@ -395,7 +395,7 @@ struct hfs_bnode *hfs_bmap_alloc(struct
off += node->page_offset;
pagep = node->page + (off >> PAGE_SHIFT);
- data = kmap(*pagep);
+ data = kmap_local_page(*pagep);
off &= ~PAGE_MASK;
idx = 0;
@@ -408,7 +408,7 @@ struct hfs_bnode *hfs_bmap_alloc(struct
idx += i;
data[off] |= m;
set_page_dirty(*pagep);
- kunmap(*pagep);
+ kunmap_local(data);
tree->free_nodes--;
mark_inode_dirty(tree->inode);
hfs_bnode_put(node);
@@ -418,14 +418,14 @@ struct hfs_bnode *hfs_bmap_alloc(struct
}
}
if (++off >= PAGE_SIZE) {
- kunmap(*pagep);
- data = kmap(*++pagep);
+ kunmap_local(data);
+ data = kmap_local_page(*++pagep);
off = 0;
}
idx += 8;
len--;
}
- kunmap(*pagep);
+ kunmap_local(data);
nidx = node->next;
if (!nidx) {
hfs_dbg(BNODE_MOD, "create new bmap node\n");
@@ -441,7 +441,7 @@ struct hfs_bnode *hfs_bmap_alloc(struct
off = off16;
off += node->page_offset;
pagep = node->page + (off >> PAGE_SHIFT);
- data = kmap(*pagep);
+ data = kmap_local_page(*pagep);
off &= ~PAGE_MASK;
}
}
@@ -491,7 +491,7 @@ void hfs_bmap_free(struct hfs_bnode *nod
}
off += node->page_offset + nidx / 8;
page = node->page[off >> PAGE_SHIFT];
- data = kmap(page);
+ data = kmap_local_page(page);
off &= ~PAGE_MASK;
m = 1 << (~nidx & 7);
byte = data[off];
@@ -499,13 +499,13 @@ void hfs_bmap_free(struct hfs_bnode *nod
pr_crit("trying to free free bnode "
"%u(%d)\n",
node->this, node->type);
- kunmap(page);
+ kunmap_local(data);
hfs_bnode_put(node);
return;
}
data[off] = byte & ~m;
set_page_dirty(page);
- kunmap(page);
+ kunmap_local(data);
hfs_bnode_put(node);
tree->free_nodes++;
mark_inode_dirty(tree->inode);
_
Patches currently in -mm which might be from fmdefrancesco@xxxxxxxxx are
