From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- fs/squashfs/zlib_wrapper.c | 137 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 fs/squashfs/zlib_wrapper.c (limited to 'fs/squashfs/zlib_wrapper.c') diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c new file mode 100644 index 000000000..a29001311 --- /dev/null +++ b/fs/squashfs/zlib_wrapper.c @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Squashfs - a compressed read only filesystem for Linux + * + * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 + * Phillip Lougher + * + * zlib_wrapper.c + */ + + +#include +#include +#include +#include +#include + +#include "squashfs_fs.h" +#include "squashfs_fs_sb.h" +#include "squashfs.h" +#include "decompressor.h" +#include "page_actor.h" + +static void *zlib_init(struct squashfs_sb_info *dummy, void *buff) +{ + z_stream *stream = kmalloc_obj(z_stream); + if (stream == NULL) + goto failed; + stream->workspace = vmalloc(zlib_inflate_workspacesize()); + if (stream->workspace == NULL) + goto failed; + + return stream; + +failed: + ERROR("Failed to allocate zlib workspace\n"); + kfree(stream); + return ERR_PTR(-ENOMEM); +} + + +static void zlib_free(void *strm) +{ + z_stream *stream = strm; + + if (stream) + vfree(stream->workspace); + kfree(stream); +} + + +static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm, + struct bio *bio, int offset, int length, + struct squashfs_page_actor *output) +{ + struct bvec_iter_all iter_all = {}; + struct bio_vec *bvec = bvec_init_iter_all(&iter_all); + int zlib_init = 0, error = 0; + z_stream *stream = strm; + + stream->avail_out = PAGE_SIZE; + stream->next_out = squashfs_first_page(output); + stream->avail_in = 0; + + if (IS_ERR(stream->next_out)) { + error = PTR_ERR(stream->next_out); + goto finish; + } + + for (;;) { + int zlib_err; + + if (stream->avail_in == 0) { + const void *data; + int avail; + + if (!bio_next_segment(bio, &iter_all)) { + /* Z_STREAM_END must be reached. */ + error = -EIO; + break; + } + + avail = min(length, ((int)bvec->bv_len) - offset); + data = bvec_virt(bvec); + length -= avail; + stream->next_in = data + offset; + stream->avail_in = avail; + offset = 0; + } + + if (stream->avail_out == 0) { + stream->next_out = squashfs_next_page(output); + if (IS_ERR(stream->next_out)) { + error = PTR_ERR(stream->next_out); + break; + } else if (stream->next_out != NULL) + stream->avail_out = PAGE_SIZE; + } + + if (!zlib_init) { + zlib_err = zlib_inflateInit(stream); + if (zlib_err != Z_OK) { + error = -EIO; + break; + } + zlib_init = 1; + } + + zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH); + if (zlib_err == Z_STREAM_END) + break; + if (zlib_err != Z_OK) { + error = -EIO; + break; + } + } + +finish: + squashfs_finish_page(output); + + if (!error) + if (zlib_inflateEnd(stream) != Z_OK) + error = -EIO; + + return error ? error : stream->total_out; +} + +const struct squashfs_decompressor squashfs_zlib_comp_ops = { + .init = zlib_init, + .free = zlib_free, + .decompress = zlib_uncompress, + .id = ZLIB_COMPRESSION, + .name = "zlib", + .alloc_buffer = 1, + .supported = 1 +}; + -- cgit v1.3.1