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btrfs: zlib: replace kmap() with kmap_local_page() in zlib_compress_pages()

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The use of kmap() is being deprecated in favor of kmap_local_page(). With
kmap_local_page(), the mapping is per thread, CPU local and not globally
visible.

Therefore, use kmap_local_page() / kunmap_local() in zlib_compress_pages()
because in this function the mappings are per thread and are not visible
in other contexts. Furthermore, drop the mappings of "out_page" which is
allocated within zlib_compress_pages() with alloc_page(GFP_NOFS) and use
page_address().

Tested with xfstests on a QEMU + KVM 32-bits VM with 4GB of RAM booting
a kernel with HIGHMEM64G enabled. This patch passes 26/26 tests of group
"compress".

CC: Qu Wenruo <wqu@suse.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Fabio M. De Francesco 2022-06-27 18:33:05 +02:00 committed by David Sterba
parent ebd23482ef
commit 718e58551a
1 changed files with 13 additions and 19 deletions
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32
fs/btrfs/zlib.c
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@ -97,7 +97,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret;
char *data_in;
char *data_in = NULL;
char *cpage_out;
int nr_pages = 0;
struct page *in_page = NULL;
@ -126,7 +126,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
ret = -ENOMEM;
goto out;
}
cpage_out = kmap(out_page);
cpage_out = page_address(out_page);
pages[0] = out_page;
nr_pages = 1;
@ -148,26 +148,26 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
int i;
for (i = 0; i < in_buf_pages; i++) {
if (in_page) {
kunmap(in_page);
if (data_in) {
kunmap_local(data_in);
put_page(in_page);
}
in_page = find_get_page(mapping,
start >> PAGE_SHIFT);
data_in = kmap(in_page);
data_in = kmap_local_page(in_page);
memcpy(workspace->buf + i * PAGE_SIZE,
data_in, PAGE_SIZE);
start += PAGE_SIZE;
}
workspace->strm.next_in = workspace->buf;
} else {
if (in_page) {
kunmap(in_page);
if (data_in) {
kunmap_local(data_in);
put_page(in_page);
}
in_page = find_get_page(mapping,
start >> PAGE_SHIFT);
data_in = kmap(in_page);
data_in = kmap_local_page(in_page);
start += PAGE_SIZE;
workspace->strm.next_in = data_in;
}
@ -196,9 +196,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
* the stream end if required
*/
if (workspace->strm.avail_out == 0) {
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
@ -207,7 +205,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
ret = -ENOMEM;
goto out;
}
cpage_out = kmap(out_page);
cpage_out = page_address(out_page);
pages[nr_pages] = out_page;
nr_pages++;
workspace->strm.avail_out = PAGE_SIZE;
@ -234,9 +232,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
goto out;
} else if (workspace->strm.avail_out == 0) {
/* get another page for the stream end */
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
@ -245,7 +241,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
ret = -ENOMEM;
goto out;
}
cpage_out = kmap(out_page);
cpage_out = page_address(out_page);
pages[nr_pages] = out_page;
nr_pages++;
workspace->strm.avail_out = PAGE_SIZE;
@ -264,13 +260,11 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
*total_in = workspace->strm.total_in;
out:
*out_pages = nr_pages;
if (out_page)
kunmap(out_page);
if (in_page) {
kunmap(in_page);
if (data_in) {
kunmap_local(data_in);
put_page(in_page);
}
return ret;
}