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btrfs: zstd: replace kmap() with kmap_local_page()

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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 zstd.c because in this
file the mappings are per thread and are not visible in other contexts. In
the meanwhile use plain page_address() on output pages allocated with
the GFP_NOFS flag instead of calling kmap*() on them (since they are
always allocated from ZONE_NORMAL).

Tested with xfstests on QEMU + KVM 32 bits VM with 4GB of RAM, booting a
kernel with HIGHMEM64G enabled.

Suggested-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 2022-07-06 13:15:20 +02:00 committed by David Sterba
parent 39ade048a3
commit ebd23482ef
1 changed files with 13 additions and 20 deletions
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33
fs/btrfs/zstd.c
View File

@ -403,7 +403,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
/* map in the first page of input data */
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
workspace->in_buf.src = kmap(in_page);
workspace->in_buf.src = kmap_local_page(in_page);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
@ -415,7 +415,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.dst = page_address(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
@ -450,9 +450,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
if (workspace->out_buf.pos == workspace->out_buf.size) {
tot_out += PAGE_SIZE;
max_out -= PAGE_SIZE;
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
@ -462,7 +460,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.dst = page_address(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out,
PAGE_SIZE);
@ -477,13 +475,12 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
/* Check if we need more input */
if (workspace->in_buf.pos == workspace->in_buf.size) {
tot_in += PAGE_SIZE;
kunmap(in_page);
kunmap_local(workspace->in_buf.src);
put_page(in_page);
start += PAGE_SIZE;
len -= PAGE_SIZE;
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
workspace->in_buf.src = kmap(in_page);
workspace->in_buf.src = kmap_local_page(in_page);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
}
@ -510,9 +507,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
tot_out += PAGE_SIZE;
max_out -= PAGE_SIZE;
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
@ -522,7 +517,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.dst = page_address(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
}
@ -537,13 +532,10 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
*total_out = tot_out;
out:
*out_pages = nr_pages;
/* Cleanup */
if (in_page) {
kunmap(in_page);
if (workspace->in_buf.src) {
kunmap_local(workspace->in_buf.src);
put_page(in_page);
}
if (out_page)
kunmap(out_page);
return ret;
}
@ -567,7 +559,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
goto done;
}
workspace->in_buf.src = kmap(pages_in[page_in_index]);
workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
@ -603,14 +595,15 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
break;
if (workspace->in_buf.pos == workspace->in_buf.size) {
kunmap(pages_in[page_in_index++]);
kunmap_local(workspace->in_buf.src);
page_in_index++;
if (page_in_index >= total_pages_in) {
workspace->in_buf.src = NULL;
ret = -EIO;
goto done;
}
srclen -= PAGE_SIZE;
workspace->in_buf.src = kmap(pages_in[page_in_index]);
workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
}
@ -619,7 +612,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
zero_fill_bio(cb->orig_bio);
done:
if (workspace->in_buf.src)
kunmap(pages_in[page_in_index]);
kunmap_local(workspace->in_buf.src);
return ret;
}