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squashfs: support reading fragments in readahead call 

Add a function which can be used to read fragments in the readahead call.

This function is necessary because filesystems built with the -tailends
(or -always-use-fragments) option may have fragments present which cannot
be currently handled.

Link: https://lkml.kernel.org/r/20220617083810.337573-5-hsinyi@chromium.org
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Xiongwei Song <Xiongwei.Song@windriver.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Zheng Liang <zhengliang6@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Phillip Lougher 2022-06-17 16:38:15 +08:00 committed by akpm
parent 8fc78b6fe2
commit b09a7a036d
1 changed files with 44 additions and 3 deletions
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47
fs/squashfs/file.c
View File

@ -496,6 +496,41 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
return 0;
}
static int squashfs_readahead_fragment(struct page **page,
unsigned int pages, unsigned int expected)
{
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;
if (buffer->error)
goto out;
expected += squashfs_i(inode)->fragment_offset;
for (n = 0; n < pages; n++) {
unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
unsigned int offset = base + squashfs_i(inode)->fragment_offset;
if (expected > offset) {
unsigned int avail = min_t(unsigned int, expected -
offset, PAGE_SIZE);
squashfs_fill_page(page[n], buffer, offset, avail);
}
unlock_page(page[n]);
put_page(page[n]);
}
out:
squashfs_cache_put(buffer);
return buffer->error;
}
static void squashfs_readahead(struct readahead_control *ractl)
{
struct inode *inode = ractl->mapping->host;
@ -512,9 +547,6 @@ static void squashfs_readahead(struct readahead_control *ractl)
readahead_expand(ractl, start, (len | mask) + 1);
if (file_end == 0)
return;
pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
if (!pages)
return;
@ -540,6 +572,15 @@ static void squashfs_readahead(struct readahead_control *ractl)
(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,
expected);
if (res)
goto skip_pages;
continue;
}
bsize = read_blocklist(inode, index, &block);
if (bsize == 0)
goto skip_pages;