From c9199de82bad03bceb94ec3c5195c879d7e11911 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Thu, 20 Oct 2022 23:36:15 +0100 Subject: [PATCH] squashfs: fix extending readahead beyond end of file 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 Tested-by: Bagas Sanjaya Reported-by: Marc Miltenberger Cc: Dimitri John Ledkov Cc: Hsin-Yi Wang Cc: Mirsad Goran Todorovac Cc: Slade Watkins Cc: Thorsten Leemhuis Cc: Signed-off-by: Andrew Morton --- fs/squashfs/file.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index e526eb7a1658..f0afd4d6fd30 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -559,6 +559,12 @@ static void squashfs_readahead(struct readahead_control *ractl) 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 readahead_control *ractl) 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,