From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
Nick Terrell <terrelln@fb.com>,
linux-btrfs@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Kees Cook <keescook@chromium.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"James E. J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Helge Deller <deller@gmx.de>,
John David Anglin <dave.anglin@bell.net>,
linux-parisc@vger.kernel.org
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Filipe Manana <fdmanana@kernel.org>
Subject: [PATCH v6 2/2] btrfs: Replace kmap() with kmap_local_page() in zstd.c
Date: Wed, 6 Jul 2022 13:15:20 +0200 [thread overview]
Message-ID: <20220706111520.12858-3-fmdefrancesco@gmail.com> (raw)
In-Reply-To: <20220706111520.12858-1-fmdefrancesco@gmail.com>
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 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.
Cc: Filipe Manana <fdmanana@kernel.org>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
fs/btrfs/zstd.c | 33 +++++++++++++--------------------
1 file changed, 13 insertions(+), 20 deletions(-)
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 0fe31a6f6e68..35a0224d4eb7 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -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;
}
--
2.36.1
next prev parent reply other threads:[~2022-07-06 11:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-06 11:15 [PATCH v6 0/2] btrfs: Replace kmap() with kmap_local_page() in zstd.c Fabio M. De Francesco
2022-07-06 11:15 ` [PATCH v6 1/2] highmem: Make __kunmap_{local,atomic}() take "const void *" Fabio M. De Francesco
2022-07-06 19:07 ` Andrew Morton
2022-07-08 12:47 ` Helge Deller
2022-07-06 11:15 ` Fabio M. De Francesco [this message]
2022-07-07 22:12 ` [PATCH v6 0/2] btrfs: Replace kmap() with kmap_local_page() in zstd.c David Sterba
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