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https://github.com/torvalds/linux
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675f02e5e6
Remove use of page APIs, return the errno instead of 0, switch from kmap_atomic to kmap_local and use folio_end_read() to unify the two exit paths. Link: https://lkml.kernel.org/r/20240420025029.2166544-23-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Phillip Lougher <phillip@squashfs.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
110 lines
3 KiB
C
110 lines
3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* symlink.c
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*/
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/*
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* This file implements code to handle symbolic links.
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*
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* The data contents of symbolic links are stored inside the symbolic
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* link inode within the inode table. This allows the normally small symbolic
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* link to be compressed as part of the inode table, achieving much greater
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* compression than if the symbolic link was compressed individually.
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*/
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#include <linux/fs.h>
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#include <linux/vfs.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/pagemap.h>
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#include <linux/xattr.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs_fs_i.h"
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#include "squashfs.h"
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#include "xattr.h"
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static int squashfs_symlink_read_folio(struct file *file, struct folio *folio)
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{
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struct inode *inode = folio->mapping->host;
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struct super_block *sb = inode->i_sb;
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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int index = folio_pos(folio);
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u64 block = squashfs_i(inode)->start;
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int offset = squashfs_i(inode)->offset;
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int length = min_t(int, i_size_read(inode) - index, PAGE_SIZE);
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int bytes, copied, error;
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void *pageaddr;
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struct squashfs_cache_entry *entry;
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TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
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"%llx, offset %x\n", folio->index, block, offset);
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/*
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* Skip index bytes into symlink metadata.
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*/
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if (index) {
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bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
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index);
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if (bytes < 0) {
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ERROR("Unable to read symlink [%llx:%x]\n",
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squashfs_i(inode)->start,
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squashfs_i(inode)->offset);
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error = bytes;
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goto out;
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}
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}
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/*
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* Read length bytes from symlink metadata. Squashfs_read_metadata
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* is not used here because it can sleep and we want to use
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* kmap_local to map the folio. Instead call the underlying
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* squashfs_cache_get routine. As length bytes may overlap metadata
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* blocks, we may need to call squashfs_cache_get multiple times.
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*/
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for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
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entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
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if (entry->error) {
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ERROR("Unable to read symlink [%llx:%x]\n",
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squashfs_i(inode)->start,
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squashfs_i(inode)->offset);
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squashfs_cache_put(entry);
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error = entry->error;
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goto out;
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}
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pageaddr = kmap_local_folio(folio, 0);
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copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
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length - bytes);
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if (copied == length - bytes)
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memset(pageaddr + length, 0, PAGE_SIZE - length);
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else
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block = entry->next_index;
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kunmap_local(pageaddr);
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squashfs_cache_put(entry);
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}
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flush_dcache_folio(folio);
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error = 0;
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out:
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folio_end_read(folio, error == 0);
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return error;
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}
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const struct address_space_operations squashfs_symlink_aops = {
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.read_folio = squashfs_symlink_read_folio
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};
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const struct inode_operations squashfs_symlink_inode_ops = {
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.get_link = page_get_link,
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.listxattr = squashfs_listxattr
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};
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