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Squashfs: Rewrite and update squashfs_readahead_fragment() to not use page->index

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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@squashfs.org.uk>
Link: https://lore.kernel.org/r/20240818235847.170468-5-phillip@squashfs.org.uk
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Phillip Lougher 2024-08-19 00:58:47 +01:00 committed by Christian Brauner
parent 7f73fcde4d
commit fd54fa6efe
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 50 additions and 16 deletions
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66
fs/squashfs/file.c
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@ -494,39 +494,73 @@ out:
}
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;