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Message-Id: <20240818235847.170468-5-phillip@squashfs.org.uk>
Date: Mon, 19 Aug 2024 00:58:47 +0100
From: Phillip Lougher <phillip@...ashfs.org.uk>
To: akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Cc: willy@...radead.org,
lizetao1@...wei.com,
Phillip Lougher <phillip@...ashfs.org.uk>
Subject: [PATCH 4/4] Squashfs: Rewrite and update squashfs_readahead_fragment() to not use page->index
The previous implementation lacked error checking (e.g. the bytes
returned by squashfs_fill_page() is not checked), and the use of
page->index could not be removed without substantially rewriting
the routine to use the page actor abstraction used elsewhere.
Signed-off-by: Phillip Lougher <phillip@...ashfs.org.uk>
---
fs/squashfs/file.c | 66 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 50 insertions(+), 16 deletions(-)
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 50fe5a078b83..5a3745e52025 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -494,39 +494,73 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
}
static int squashfs_readahead_fragment(struct page **page,
- unsigned int pages, unsigned int expected)
+ unsigned int pages, unsigned int expected, loff_t start)
{
struct inode *inode = page[0]->mapping->host;
struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
squashfs_i(inode)->fragment_block,
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 error = buffer->error;
+ int i, bytes, copied;
+ struct squashfs_page_actor *actor;
+ unsigned int offset;
+ void *addr;
+ struct page *last_page;
- if (error)
+ if (buffer->error)
goto out;
- expected += squashfs_i(inode)->fragment_offset;
+ actor = squashfs_page_actor_init_special(msblk, page, pages,
+ expected, start);
+ if (!actor)
+ goto out;
- for (n = 0; n < pages; n++) {
- unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
- unsigned int offset = base + squashfs_i(inode)->fragment_offset;
+ squashfs_actor_nobuff(actor);
+ addr = squashfs_first_page(actor);
- if (expected > offset) {
- unsigned int avail = min_t(unsigned int, expected -
- offset, PAGE_SIZE);
+ for (copied = offset = 0; offset < expected; offset += PAGE_SIZE) {
+ int avail = min_t(int, expected - offset, PAGE_SIZE);
- squashfs_fill_page(page[n], buffer, offset, avail);
+ if (!IS_ERR(addr)) {
+ bytes = squashfs_copy_data(addr, buffer, offset +
+ squashfs_i(inode)->fragment_offset, avail);
+
+ if (bytes != avail)
+ goto failed;
}
- unlock_page(page[n]);
- put_page(page[n]);
+ copied += avail;
+ addr = squashfs_next_page(actor);
}
+ last_page = squashfs_page_actor_free(actor);
+
+ if (copied == expected) {
+ /* Last page (if present) may have trailing bytes not filled */
+ bytes = copied % PAGE_SIZE;
+ if (bytes && last_page)
+ memzero_page(last_page, bytes, PAGE_SIZE - bytes);
+
+ for (i = 0; i < pages; i++) {
+ flush_dcache_page(page[i]);
+ SetPageUptodate(page[i]);
+ }
+ }
+
+ for (i = 0; i < pages; i++) {
+ unlock_page(page[i]);
+ put_page(page[i]);
+ }
+
+ squashfs_cache_put(buffer);
+ return 0;
+
+failed:
+ squashfs_page_actor_free(actor);
+
out:
squashfs_cache_put(buffer);
- return error;
+ return 1;
}
static void squashfs_readahead(struct readahead_control *ractl)
@@ -572,7 +606,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
if (start >> msblk->block_log == file_end &&
squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) {
res = squashfs_readahead_fragment(pages, nr_pages,
- expected);
+ expected, start);
if (res)
goto skip_pages;
continue;
--
2.39.2
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