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![Chandan Rajendra](/assets/img/avatar_default.png)
Define new structures to represent overlay instance lower layers and overlay merge dir lower layers to make room for storing more per layer information in-memory. Instead of keeping the fs instance lower layers in an array of struct vfsmount, keep them in an array of new struct ovl_layer, that has a pointer to struct vfsmount. Instead of keeping the dentry lower layers in an array of struct path, keep them in an array of new struct ovl_path, that has a pointer to struct dentry and to struct ovl_layer. Add a small helper to find the fs layer id that correspopnds to a lower struct ovl_path and use it in ovl_lookup(). [amir: split re-structure from anonymous bdev patch] Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
598 lines
14 KiB
C
598 lines
14 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 <linux/namei.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.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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if (oe->numlower) {
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path->mnt = oe->lowerstack[0].layer->mnt;
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path->dentry = oe->lowerstack[0].dentry;
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} else {
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*path = (struct path) { };
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}
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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 dentry *ovl_i_dentry_upper(struct inode *inode)
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{
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return ovl_upperdentry_dereference(OVL_I(inode));
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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_i_dentry_upper(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 inode *inode)
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{
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return OVL_I(inode)->cache;
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}
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void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
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{
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OVL_I(inode)->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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/*
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* For hard links it's possible for ovl_dentry_upper() to return positive, while
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* there's no actual upper alias for the inode. Copy up code needs to know
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* about the existence of the upper alias, so it can't use ovl_dentry_upper().
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*/
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bool ovl_dentry_has_upper_alias(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->has_upper;
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}
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void ovl_dentry_set_upper_alias(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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oe->has_upper = 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, bool impurity)
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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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/*
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* Version is used by readdir code to keep cache consistent. For merge
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* dirs all changes need to be noted. For non-merge dirs, cache only
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* contains impure (ones which have been copied up and have origins)
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* entries, so only need to note changes to impure entries.
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*/
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if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity)
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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_has_upper_alias(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_origin_xattr(struct dentry *dentry)
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{
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int res;
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res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
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/* Zero size value means "copied up but origin unknown" */
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if (res >= 0)
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return true;
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return false;
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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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void ovl_clear_flag(unsigned long flag, struct inode *inode)
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{
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clear_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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/* Caller must hold OVL_I(inode)->lock */
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static void ovl_cleanup_index(struct dentry *dentry)
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{
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struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
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struct dentry *lowerdentry = ovl_dentry_lower(dentry);
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struct dentry *upperdentry = ovl_dentry_upper(dentry);
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struct dentry *index = NULL;
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struct inode *inode;
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struct qstr name;
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int err;
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err = ovl_get_index_name(lowerdentry, &name);
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if (err)
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goto fail;
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inode = d_inode(upperdentry);
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if (inode->i_nlink != 1) {
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pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
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upperdentry, inode->i_ino, inode->i_nlink);
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/*
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* We either have a bug with persistent union nlink or a lower
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* hardlink was added while overlay is mounted. Adding a lower
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* hardlink and then unlinking all overlay hardlinks would drop
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* overlay nlink to zero before all upper inodes are unlinked.
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* As a safety measure, when that situation is detected, set
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* the overlay nlink to the index inode nlink minus one for the
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* index entry itself.
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*/
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set_nlink(d_inode(dentry), inode->i_nlink - 1);
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ovl_set_nlink_upper(dentry);
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goto out;
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}
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inode_lock_nested(dir, I_MUTEX_PARENT);
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/* TODO: whiteout instead of cleanup to block future open by handle */
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index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
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err = PTR_ERR(index);
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if (!IS_ERR(index))
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err = ovl_cleanup(dir, index);
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else
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index = NULL;
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inode_unlock(dir);
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if (err)
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goto fail;
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out:
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dput(index);
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return;
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fail:
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pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err);
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goto out;
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}
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/*
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* Operations that change overlay inode and upper inode nlink need to be
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* synchronized with copy up for persistent nlink accounting.
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*/
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int ovl_nlink_start(struct dentry *dentry, bool *locked)
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{
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struct ovl_inode *oi = OVL_I(d_inode(dentry));
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const struct cred *old_cred;
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int err;
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if (!d_inode(dentry) || d_is_dir(dentry))
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return 0;
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|
|
/*
|
|
* With inodes index is enabled, we store the union overlay nlink
|
|
* in an xattr on the index inode. When whiting out lower hardlinks
|
|
* we need to decrement the overlay persistent nlink, but before the
|
|
* first copy up, we have no upper index inode to store the xattr.
|
|
*
|
|
* As a workaround, before whiteout/rename over of a lower hardlink,
|
|
* copy up to create the upper index. Creating the upper index will
|
|
* initialize the overlay nlink, so it could be dropped if unlink
|
|
* or rename succeeds.
|
|
*
|
|
* TODO: implement metadata only index copy up when called with
|
|
* ovl_copy_up_flags(dentry, O_PATH).
|
|
*/
|
|
if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) &&
|
|
d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) {
|
|
err = ovl_copy_up(dentry);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = mutex_lock_interruptible(&oi->lock);
|
|
if (err)
|
|
return err;
|
|
|
|
if (!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
|
|
goto out;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
/*
|
|
* The overlay inode nlink should be incremented/decremented IFF the
|
|
* upper operation succeeds, along with nlink change of upper inode.
|
|
* Therefore, before link/unlink/rename, we store the union nlink
|
|
* value relative to the upper inode nlink in an upper inode xattr.
|
|
*/
|
|
err = ovl_set_nlink_upper(dentry);
|
|
revert_creds(old_cred);
|
|
|
|
out:
|
|
if (err)
|
|
mutex_unlock(&oi->lock);
|
|
else
|
|
*locked = true;
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_nlink_end(struct dentry *dentry, bool locked)
|
|
{
|
|
if (locked) {
|
|
if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
|
|
d_inode(dentry)->i_nlink == 0) {
|
|
const struct cred *old_cred;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
ovl_cleanup_index(dentry);
|
|
revert_creds(old_cred);
|
|
}
|
|
|
|
mutex_unlock(&OVL_I(d_inode(dentry))->lock);
|
|
}
|
|
}
|
|
|
|
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
|
|
{
|
|
/* Workdir should not be the same as upperdir */
|
|
if (workdir == upperdir)
|
|
goto err;
|
|
|
|
/* Workdir should not be subdir of upperdir and vice versa */
|
|
if (lock_rename(workdir, upperdir) != NULL)
|
|
goto err_unlock;
|
|
|
|
return 0;
|
|
|
|
err_unlock:
|
|
unlock_rename(workdir, upperdir);
|
|
err:
|
|
pr_err("overlayfs: failed to lock workdir+upperdir\n");
|
|
return -EIO;
|
|
}
|