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Message-Id: <20221020065942.1828-1-nicememory@gmail.com>
Date: Thu, 20 Oct 2022 14:59:42 +0800
From: Jintao Yin <nicememory@...il.com>
To: phillip@...ashfs.org.uk
Cc: bagasdotme@...il.com, hsinyi@...omium.org,
linux-kernel@...r.kernel.org, marcmiltenberger@...il.com,
mirsad.todorovac@....unizg.hr, nicememory@...il.com,
regressions@...mhuis.info, regressions@...ts.linux.dev,
srw@...dewatkins.net
Subject: Re: BISECT result: 6.0.0-RC kernels trigger Firefox snap bug with 6.0.0-rc3 through 6.0.0-rc7
This diff is based on Phillip's latest two patches and fixes another wrong
check of last page in file_direct.c. At the same time, improve the logic
to update the status of pages only if page actor touches them.
Please help test and feedbacks are welcome.
Hi Phillip,
If check (bytes && used_pages > 0) is enough (since bytes is non-zero only
when handling the last block) or should I caculate the real last page index
from the file size and check the page index?
Thanks,
Jintao
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index e56510964b22..5efa2a9f9630 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -506,8 +506,9 @@ static int squashfs_readahead_fragment(struct page **page,
squashfs_i(inode)->fragment_size);
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
+ int res = buffer->error;
- if (buffer->error)
+ if (res)
goto out;
expected += squashfs_i(inode)->fragment_offset;
@@ -529,7 +530,7 @@ static int squashfs_readahead_fragment(struct page **page,
out:
squashfs_cache_put(buffer);
- return buffer->error;
+ return res;
}
static void squashfs_readahead(struct readahead_control *ractl)
@@ -557,6 +558,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
int res, bsize;
u64 block = 0;
unsigned int expected;
+ int nr_used_pages;
nr_pages = __readahead_batch(ractl, pages, max_pages);
if (!nr_pages)
@@ -593,18 +595,18 @@ static void squashfs_readahead(struct readahead_control *ractl)
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
- squashfs_page_actor_free(actor);
+ nr_used_pages = squashfs_page_actor_free(actor);
if (res == expected) {
int bytes;
/* Last page (if present) may have trailing bytes not filled */
bytes = res % PAGE_SIZE;
- if (pages[nr_pages - 1]->index == file_end && bytes)
- memzero_page(pages[nr_pages - 1], bytes,
+ if (index == file_end && bytes && nr_used_pages > 0)
+ memzero_page(pages[nr_used_pages - 1], bytes,
PAGE_SIZE - bytes);
- for (i = 0; i < nr_pages; i++) {
+ for (i = 0; i < nr_used_pages; i++) {
flush_dcache_page(pages[i]);
SetPageUptodate(pages[i]);
}
diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
index f1ccad519e28..8d875d8c5709 100644
--- a/fs/squashfs/file_direct.c
+++ b/fs/squashfs/file_direct.c
@@ -30,7 +30,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
int start_index = target_page->index & ~mask;
int end_index = start_index | mask;
- int i, n, pages, bytes, res = -ENOMEM;
+ int i, n, pages, used_pages, bytes, res = -ENOMEM;
struct page **page;
struct squashfs_page_actor *actor;
void *pageaddr;
@@ -74,7 +74,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
/* Decompress directly into the page cache buffers */
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
- squashfs_page_actor_free(actor);
+ used_pages = squashfs_page_actor_free(actor);
if (res < 0)
goto mark_errored;
@@ -86,16 +86,18 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
/* Last page (if present) may have trailing bytes not filled */
bytes = res % PAGE_SIZE;
- if (page[pages - 1]->index == end_index && bytes) {
- pageaddr = kmap_local_page(page[pages - 1]);
+ if (bytes && used_pages > 0) {
+ pageaddr = kmap_local_page(page[used_pages - 1]);
memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
kunmap_local(pageaddr);
}
/* Mark pages as uptodate, unlock and release */
for (i = 0; i < pages; i++) {
- flush_dcache_page(page[i]);
- SetPageUptodate(page[i]);
+ if (i < used_pages) {
+ flush_dcache_page(page[i]);
+ SetPageUptodate(page[i]);
+ }
unlock_page(page[i]);
if (page[i] != target_page)
put_page(page[i]);
@@ -112,8 +114,10 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
for (i = 0; i < pages; i++) {
if (page[i] == NULL || page[i] == target_page)
continue;
- flush_dcache_page(page[i]);
- SetPageError(page[i]);
+ if (i < used_pages) {
+ flush_dcache_page(page[i]);
+ SetPageError(page[i]);
+ }
unlock_page(page[i]);
put_page(page[i]);
}
diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
index 95ffbb543d91..c2c5c3937ef9 100644
--- a/fs/squashfs/page_actor.h
+++ b/fs/squashfs/page_actor.h
@@ -29,10 +29,12 @@ extern struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
extern struct squashfs_page_actor *squashfs_page_actor_init_special(
struct squashfs_sb_info *msblk,
struct page **page, int pages, int length);
-static inline void squashfs_page_actor_free(struct squashfs_page_actor *actor)
+static inline int squashfs_page_actor_free(struct squashfs_page_actor *actor)
{
+ int res = actor->next_page;
kfree(actor->tmp_buffer);
kfree(actor);
+ return res;
}
static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
{
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