Squashfs: Ensure all readahead pages have been used

In the recent work to remove page->index, a sanity check
that ensured all the readhead pages were covered by the
Squashfs data block was removed [1].

To avoid any regression, this commit adds the sanity check
back in an equivalent way.  Namely the page actor will now
return error if any pages are unused after completion.

[1] https://lore.kernel.org/all/20240818235847.170468-3-phillip@squashfs.org.uk/

--

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Link: https://lore.kernel.org/r/20240822233106.121522-1-phillip@squashfs.org.uk
V3: last_page should be actor->last_page
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Phillip Lougher 2024-08-23 00:31:06 +01:00 committed by Christian Brauner
parent d937c813f8
commit 84e0e03b30
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 5 additions and 4 deletions

View File

@ -535,7 +535,7 @@ static int squashfs_readahead_fragment(struct page **page,
last_page = squashfs_page_actor_free(actor);
if (copied == expected) {
if (copied == expected && !IS_ERR(last_page)) {
/* Last page (if present) may have trailing bytes not filled */
bytes = copied % PAGE_SIZE;
if (bytes && last_page)
@ -625,7 +625,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
last_page = squashfs_page_actor_free(actor);
if (res == expected) {
if (res == expected && !IS_ERR(last_page)) {
int bytes;
/* Last page (if present) may have trailing bytes not filled */

View File

@ -80,7 +80,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
if (res < 0)
goto mark_errored;
if (res != expected) {
if (res != expected || IS_ERR(last_page)) {
res = -EIO;
goto mark_errored;
}

View File

@ -33,10 +33,11 @@ extern struct squashfs_page_actor *squashfs_page_actor_init_special(
loff_t start_index);
static inline struct page *squashfs_page_actor_free(struct squashfs_page_actor *actor)
{
struct page *last_page = actor->last_page;
struct page *last_page = actor->next_page == actor->pages ? actor->last_page : ERR_PTR(-EIO);
kfree(actor->tmp_buffer);
kfree(actor);
return last_page;
}
static inline void *squashfs_first_page(struct squashfs_page_actor *actor)