| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20211007170605.7062-4-xiang@kernel.org>
Date: Fri, 8 Oct 2021 01:06:05 +0800
From: Gao Xiang <xiang@...nel.org>
To: linux-erofs@...ts.ozlabs.org, Chao Yu <chao@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Gao Xiang <hsiangkao@...ux.alibaba.com>
Subject: [PATCH 3/3] erofs: introduce readmore decompression strategy
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
Previously, the requested read length is strictly followed by EROFS
decompression strategy. However, it's quite inefficient to apply
partial decompression if non-negligible data in big pclusters needs
to be handled, especially for the upcoming LZMA algorithm.
Let's decompress more for the cases above as what other fses did.
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
fs/erofs/internal.h | 16 ++++++++
fs/erofs/zdata.c | 94 ++++++++++++++++++++++++++++++++++++---------
fs/erofs/zmap.c | 4 +-
3 files changed, 94 insertions(+), 20 deletions(-)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 48bfc6eb2b02..e7378795a26c 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -307,6 +307,19 @@ static inline unsigned int erofs_inode_datalayout(unsigned int value)
EROFS_I_DATALAYOUT_BITS);
}
+/*
+ * Different from grab_cache_page_nowait(), reclaiming is never triggered
+ * when allocating new pages.
+ */
+static inline
+struct page *erofs_grab_cache_page_nowait(struct address_space *mapping,
+ pgoff_t index)
+{
+ return pagecache_get_page(mapping, index,
+ FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+ readahead_gfp_mask(mapping) & ~__GFP_RECLAIM);
+}
+
extern const struct super_operations erofs_sops;
extern const struct address_space_operations erofs_raw_access_aops;
@@ -368,6 +381,8 @@ struct erofs_map_blocks {
* approach instead if possible since it's more metadata lightweight.)
*/
#define EROFS_GET_BLOCKS_FIEMAP 0x0002
+/* Used to map the whole extent if non-negligible data is already requested */
+#define EROFS_GET_BLOCKS_READMORE 0x0004
enum {
Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
@@ -375,6 +390,7 @@ enum {
};
/* zmap.c */
+#define Z_EROFS_LZ4_READMORE_THRESHOLD (9 * EROFS_BLKSIZ)
extern const struct iomap_ops z_erofs_iomap_report_ops;
#ifdef CONFIG_EROFS_FS_ZIP
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 5c34ef66677f..a1861a9acfd0 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1377,6 +1377,67 @@ static void z_erofs_runqueue(struct super_block *sb,
z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
}
+static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
+ struct readahead_control *rac,
+ erofs_off_t end,
+ struct list_head *pagepool,
+ bool backmost)
+{
+ struct inode *const inode = f->inode;
+ struct erofs_map_blocks *const map = &f->map;
+ erofs_off_t cur;
+ int err;
+
+ if (backmost) {
+ map->m_la = end;
+ err = z_erofs_map_blocks_iter(inode, map,
+ EROFS_GET_BLOCKS_READMORE);
+ if (err)
+ return;
+ end = round_up(end, PAGE_SIZE);
+
+ /* expend ra for the trailing edge if readahead */
+ if (rac) {
+ loff_t newstart = readahead_pos(rac);
+
+ readahead_expand(rac, newstart, end - newstart);
+ return;
+ }
+ } else {
+ end = round_up(map->m_la, PAGE_SIZE);
+
+ if (!map->m_llen)
+ return;
+ }
+
+ cur = map->m_la + map->m_llen - 1;
+ while (cur >= end) {
+ pgoff_t index = cur >> PAGE_SHIFT;
+ struct page *page;
+
+ page = erofs_grab_cache_page_nowait(inode->i_mapping, index);
+ if (!page)
+ goto skip;
+
+ if (PageUptodate(page)) {
+ unlock_page(page);
+ put_page(page);
+ goto skip;
+ }
+
+ err = z_erofs_do_read_page(f, page, pagepool);
+ if (err)
+ erofs_err(inode->i_sb,
+ "readmore error at page %lu @ nid %llu",
+ index, EROFS_I(inode)->nid);
+ put_page(page);
+skip:
+ if (cur < PAGE_SIZE)
+ break;
+ cur = (index << PAGE_SHIFT) - 1;
+ }
+}
+
static int z_erofs_readpage(struct file *file, struct page *page)
{
struct inode *const inode = page->mapping->host;
@@ -1385,10 +1446,13 @@ static int z_erofs_readpage(struct file *file, struct page *page)
LIST_HEAD(pagepool);
trace_erofs_readpage(page, false);
-
f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
+ z_erofs_pcluster_readmore(&f, NULL, f.headoffset + PAGE_SIZE - 1,
+ &pagepool, true);
err = z_erofs_do_read_page(&f, page, &pagepool);
+ z_erofs_pcluster_readmore(&f, NULL, 0, &pagepool, false);
+
(void)z_erofs_collector_end(&f.clt);
/* if some compressed cluster ready, need submit them anyway */
@@ -1409,29 +1473,20 @@ static void z_erofs_readahead(struct readahead_control *rac)
{
struct inode *const inode = rac->mapping->host;
struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
-
- unsigned int nr_pages = readahead_count(rac);
- bool sync = (sbi->ctx.readahead_sync_decompress &&
- nr_pages <= sbi->ctx.max_sync_decompress_pages);
struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
struct page *page, *head = NULL;
+ unsigned int nr_pages;
LIST_HEAD(pagepool);
- trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
-
f.readahead = true;
f.headoffset = readahead_pos(rac);
- while ((page = readahead_page(rac))) {
- prefetchw(&page->flags);
-
- /*
- * A pure asynchronous readahead is indicated if
- * a PG_readahead marked page is hitted at first.
- * Let's also do asynchronous decompression for this case.
- */
- sync &= !(PageReadahead(page) && !head);
+ z_erofs_pcluster_readmore(&f, rac, f.headoffset +
+ readahead_length(rac) - 1, &pagepool, true);
+ nr_pages = readahead_count(rac);
+ trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
+ while ((page = readahead_page(rac))) {
set_page_private(page, (unsigned long)head);
head = page;
}
@@ -1450,11 +1505,12 @@ static void z_erofs_readahead(struct readahead_control *rac)
page->index, EROFS_I(inode)->nid);
put_page(page);
}
-
+ z_erofs_pcluster_readmore(&f, rac, 0, &pagepool, false);
(void)z_erofs_collector_end(&f.clt);
- z_erofs_runqueue(inode->i_sb, &f, &pagepool, sync);
-
+ z_erofs_runqueue(inode->i_sb, &f, &pagepool,
+ sbi->ctx.readahead_sync_decompress &&
+ nr_pages <= sbi->ctx.max_sync_decompress_pages);
if (f.map.mpage)
put_page(f.map.mpage);
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index a61cc7f55ef0..7f42a1c8a338 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -673,7 +673,9 @@ int z_erofs_map_blocks_iter(struct inode *inode,
else
map->m_algorithmformat = vi->z_algorithmtype[0];
- if (flags & EROFS_GET_BLOCKS_FIEMAP) {
+ if (flags & EROFS_GET_BLOCKS_FIEMAP ||
+ ((flags & EROFS_GET_BLOCKS_READMORE) &&
+ map->m_llen >= Z_EROFS_LZ4_READMORE_THRESHOLD)) {
err = z_erofs_get_extent_decompressedlen(&m);
if (!err)
map->m_flags |= EROFS_MAP_FULL_MAPPED;
--
2.20.1
Powered by blists - more mailing lists