The patch titled Subject: squashfs: fix extending readahead beyond end of file has been added to the -mm mm-hotfixes-unstable branch. Its filename is squashfs-fix-extending-readahead-beyond-end-of-file.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Phillip Lougher phillip@squashfs.org.uk Subject: squashfs: fix extending readahead beyond end of file Date: Thu, 20 Oct 2022 23:36:15 +0100
The readahead code will try to extend readahead to the entire size of the Squashfs data block.
But, it didn't take into account that the last block at the end of the file may not be a whole block. In this case, the code would extend readahead to beyond the end of the file, leaving trailing pages.
Fix this by only requesting the expected number of pages.
Link: https://lkml.kernel.org/r/20221020223616.7571-3-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Signed-off-by: Phillip Lougher phillip@squashfs.org.uk Cc: stable@vger.kernel.org Cc: Bagas Sanjaya bagasdotme@gmail.com Cc: Dimitri John Ledkov dimitri.ledkov@canonical.com Cc: Hsin-Yi Wang hsinyi@chromium.org Cc: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr Cc: Slade Watkins srw@sladewatkins.net Cc: Thorsten Leemhuis regressions@leemhuis.info Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
fs/squashfs/file.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/fs/squashfs/file.c~squashfs-fix-extending-readahead-beyond-end-of-file +++ a/fs/squashfs/file.c @@ -559,6 +559,12 @@ static void squashfs_readahead(struct re unsigned int expected; struct page *last_page;
+ expected = start >> msblk->block_log == file_end ? + (i_size_read(inode) & (msblk->block_size - 1)) : + msblk->block_size; + + max_pages = (expected + PAGE_SIZE - 1) >> PAGE_SHIFT; + nr_pages = __readahead_batch(ractl, pages, max_pages); if (!nr_pages) break; @@ -567,13 +573,10 @@ static void squashfs_readahead(struct re goto skip_pages;
index = pages[0]->index >> shift; + if ((pages[nr_pages - 1]->index >> shift) != index) goto skip_pages;
- expected = index == file_end ? - (i_size_read(inode) & (msblk->block_size - 1)) : - msblk->block_size; - if (index == file_end && squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) { res = squashfs_readahead_fragment(pages, nr_pages, _
Patches currently in -mm which might be from phillip@squashfs.org.uk are
squashfs-fix-read-regression-introduced-in-readahead-code.patch squashfs-fix-extending-readahead-beyond-end-of-file.patch squashfs-fix-buffer-release-race-condition-in-readahead-code.patch