mirror of https://gitee.com/openkylin/linux.git
394 lines
8.3 KiB
C
394 lines
8.3 KiB
C
/*
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* Copyright (C) 2011 Novell Inc.
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/uuid.h>
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#include "overlayfs.h"
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#include "ovl_entry.h"
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int ovl_want_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return mnt_want_write(ofs->upper_mnt);
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}
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void ovl_drop_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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mnt_drop_write(ofs->upper_mnt);
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}
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struct dentry *ovl_workdir(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return ofs->workdir;
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}
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const struct cred *ovl_override_creds(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return override_creds(ofs->creator_cred);
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}
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struct super_block *ovl_same_sb(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->same_sb;
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}
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bool ovl_can_decode_fh(struct super_block *sb)
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{
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return (sb->s_export_op && sb->s_export_op->fh_to_dentry &&
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!uuid_is_null(&sb->s_uuid));
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}
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struct dentry *ovl_indexdir(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->indexdir;
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}
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struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
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{
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size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
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struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
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if (oe)
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oe->numlower = numlower;
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return oe;
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}
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bool ovl_dentry_remote(struct dentry *dentry)
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{
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return dentry->d_flags &
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(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
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DCACHE_OP_REAL);
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}
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bool ovl_dentry_weird(struct dentry *dentry)
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{
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return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
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DCACHE_MANAGE_TRANSIT |
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DCACHE_OP_HASH |
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DCACHE_OP_COMPARE);
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}
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enum ovl_path_type ovl_path_type(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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enum ovl_path_type type = 0;
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if (ovl_dentry_upper(dentry)) {
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type = __OVL_PATH_UPPER;
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/*
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* Non-dir dentry can hold lower dentry of its copy up origin.
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*/
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if (oe->numlower) {
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type |= __OVL_PATH_ORIGIN;
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if (d_is_dir(dentry))
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type |= __OVL_PATH_MERGE;
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}
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} else {
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if (oe->numlower > 1)
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type |= __OVL_PATH_MERGE;
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}
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return type;
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}
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void ovl_path_upper(struct dentry *dentry, struct path *path)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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path->mnt = ofs->upper_mnt;
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path->dentry = ovl_dentry_upper(dentry);
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}
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void ovl_path_lower(struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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*path = oe->numlower ? oe->lowerstack[0] : (struct path) { };
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}
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enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
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{
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enum ovl_path_type type = ovl_path_type(dentry);
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if (!OVL_TYPE_UPPER(type))
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ovl_path_lower(dentry, path);
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else
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ovl_path_upper(dentry, path);
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return type;
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}
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struct dentry *ovl_dentry_upper(struct dentry *dentry)
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{
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return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
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}
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struct dentry *ovl_dentry_lower(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[0].dentry : NULL;
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}
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struct dentry *ovl_dentry_real(struct dentry *dentry)
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{
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return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
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}
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struct inode *ovl_inode_upper(struct inode *inode)
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{
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struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode));
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return upperdentry ? d_inode(upperdentry) : NULL;
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}
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struct inode *ovl_inode_lower(struct inode *inode)
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{
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return OVL_I(inode)->lower;
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}
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struct inode *ovl_inode_real(struct inode *inode)
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{
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return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
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}
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struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
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{
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return OVL_I(d_inode(dentry))->cache;
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}
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void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
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{
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OVL_I(d_inode(dentry))->cache = cache;
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}
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bool ovl_dentry_is_opaque(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->opaque;
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}
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bool ovl_dentry_is_whiteout(struct dentry *dentry)
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{
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return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
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}
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void ovl_dentry_set_opaque(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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oe->opaque = true;
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}
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bool ovl_redirect_dir(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.redirect_dir && !ofs->noxattr;
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}
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const char *ovl_dentry_get_redirect(struct dentry *dentry)
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{
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return OVL_I(d_inode(dentry))->redirect;
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}
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void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
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{
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struct ovl_inode *oi = OVL_I(d_inode(dentry));
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kfree(oi->redirect);
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oi->redirect = redirect;
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}
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void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
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struct dentry *lowerdentry)
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{
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if (upperdentry)
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OVL_I(inode)->__upperdentry = upperdentry;
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if (lowerdentry)
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OVL_I(inode)->lower = d_inode(lowerdentry);
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ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
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}
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void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
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{
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struct inode *upperinode = d_inode(upperdentry);
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WARN_ON(OVL_I(inode)->__upperdentry);
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/*
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* Make sure upperdentry is consistent before making it visible
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*/
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smp_wmb();
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OVL_I(inode)->__upperdentry = upperdentry;
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if (!S_ISDIR(upperinode->i_mode) && inode_unhashed(inode)) {
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inode->i_private = upperinode;
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__insert_inode_hash(inode, (unsigned long) upperinode);
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}
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}
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void ovl_dentry_version_inc(struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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WARN_ON(!inode_is_locked(inode));
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OVL_I(inode)->version++;
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}
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u64 ovl_dentry_version_get(struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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WARN_ON(!inode_is_locked(inode));
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return OVL_I(inode)->version;
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}
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bool ovl_is_whiteout(struct dentry *dentry)
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{
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struct inode *inode = dentry->d_inode;
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return inode && IS_WHITEOUT(inode);
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}
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struct file *ovl_path_open(struct path *path, int flags)
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{
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return dentry_open(path, flags | O_NOATIME, current_cred());
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}
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int ovl_copy_up_start(struct dentry *dentry)
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{
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struct ovl_inode *oi = OVL_I(d_inode(dentry));
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int err;
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err = mutex_lock_interruptible(&oi->lock);
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if (!err && ovl_dentry_upper(dentry)) {
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err = 1; /* Already copied up */
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mutex_unlock(&oi->lock);
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}
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return err;
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}
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void ovl_copy_up_end(struct dentry *dentry)
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{
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mutex_unlock(&OVL_I(d_inode(dentry))->lock);
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}
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bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
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{
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int res;
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char val;
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if (!d_is_dir(dentry))
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return false;
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res = vfs_getxattr(dentry, name, &val, 1);
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if (res == 1 && val == 'y')
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return true;
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return false;
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}
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int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
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const char *name, const void *value, size_t size,
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int xerr)
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{
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int err;
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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if (ofs->noxattr)
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return xerr;
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err = ovl_do_setxattr(upperdentry, name, value, size, 0);
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if (err == -EOPNOTSUPP) {
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pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
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ofs->noxattr = true;
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return xerr;
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}
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return err;
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}
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int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
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{
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int err;
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if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
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return 0;
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/*
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* Do not fail when upper doesn't support xattrs.
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* Upper inodes won't have origin nor redirect xattr anyway.
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*/
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err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
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"y", 1, 0);
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if (!err)
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ovl_set_flag(OVL_IMPURE, d_inode(dentry));
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return err;
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}
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void ovl_set_flag(unsigned long flag, struct inode *inode)
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{
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set_bit(flag, &OVL_I(inode)->flags);
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}
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bool ovl_test_flag(unsigned long flag, struct inode *inode)
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{
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return test_bit(flag, &OVL_I(inode)->flags);
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}
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/**
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* Caller must hold a reference to inode to prevent it from being freed while
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* it is marked inuse.
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*/
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bool ovl_inuse_trylock(struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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bool locked = false;
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spin_lock(&inode->i_lock);
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if (!(inode->i_state & I_OVL_INUSE)) {
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inode->i_state |= I_OVL_INUSE;
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locked = true;
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}
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spin_unlock(&inode->i_lock);
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return locked;
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}
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void ovl_inuse_unlock(struct dentry *dentry)
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{
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if (dentry) {
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struct inode *inode = d_inode(dentry);
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spin_lock(&inode->i_lock);
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WARN_ON(!(inode->i_state & I_OVL_INUSE));
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inode->i_state &= ~I_OVL_INUSE;
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spin_unlock(&inode->i_lock);
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}
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}
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