diff options
Diffstat (limited to 'fs/sdcardfs/lookup.c')
| -rw-r--r-- | fs/sdcardfs/lookup.c | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/fs/sdcardfs/lookup.c b/fs/sdcardfs/lookup.c new file mode 100644 index 000000000000..d271617290ee --- /dev/null +++ b/fs/sdcardfs/lookup.c @@ -0,0 +1,406 @@ +/* + * fs/sdcardfs/lookup.c + * + * Copyright (c) 2013 Samsung Electronics Co. Ltd + * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun, + * Sunghwan Yun, Sungjong Seo + * + * This program has been developed as a stackable file system based on + * the WrapFS which written by + * + * Copyright (c) 1998-2011 Erez Zadok + * Copyright (c) 2009 Shrikar Archak + * Copyright (c) 2003-2011 Stony Brook University + * Copyright (c) 2003-2011 The Research Foundation of SUNY + * + * This file is dual licensed. It may be redistributed and/or modified + * under the terms of the Apache 2.0 License OR version 2 of the GNU + * General Public License. + */ + +#include "sdcardfs.h" +#include "linux/delay.h" + +/* The dentry cache is just so we have properly sized dentries */ +static struct kmem_cache *sdcardfs_dentry_cachep; + +int sdcardfs_init_dentry_cache(void) +{ + sdcardfs_dentry_cachep = + kmem_cache_create("sdcardfs_dentry", + sizeof(struct sdcardfs_dentry_info), + 0, SLAB_RECLAIM_ACCOUNT, NULL); + + return sdcardfs_dentry_cachep ? 0 : -ENOMEM; +} + +void sdcardfs_destroy_dentry_cache(void) +{ + if (sdcardfs_dentry_cachep) + kmem_cache_destroy(sdcardfs_dentry_cachep); +} + +void free_dentry_private_data(struct dentry *dentry) +{ + if (!dentry || !dentry->d_fsdata) + return; + kmem_cache_free(sdcardfs_dentry_cachep, dentry->d_fsdata); + dentry->d_fsdata = NULL; +} + +/* allocate new dentry private data */ +int new_dentry_private_data(struct dentry *dentry) +{ + struct sdcardfs_dentry_info *info = SDCARDFS_D(dentry); + + /* use zalloc to init dentry_info.lower_path */ + info = kmem_cache_zalloc(sdcardfs_dentry_cachep, GFP_ATOMIC); + if (!info) + return -ENOMEM; + + spin_lock_init(&info->lock); + dentry->d_fsdata = info; + + return 0; +} + +struct inode_data { + struct inode *lower_inode; + userid_t id; +}; + +static int sdcardfs_inode_test(struct inode *inode, void *candidate_data/*void *candidate_lower_inode*/) +{ + struct inode *current_lower_inode = sdcardfs_lower_inode(inode); + userid_t current_userid = SDCARDFS_I(inode)->userid; + if (current_lower_inode == ((struct inode_data *)candidate_data)->lower_inode && + current_userid == ((struct inode_data *)candidate_data)->id) + return 1; /* found a match */ + else + return 0; /* no match */ +} + +static int sdcardfs_inode_set(struct inode *inode, void *lower_inode) +{ + /* we do actual inode initialization in sdcardfs_iget */ + return 0; +} + +struct inode *sdcardfs_iget(struct super_block *sb, struct inode *lower_inode, userid_t id) +{ + struct sdcardfs_inode_info *info; + struct inode_data data; + struct inode *inode; /* the new inode to return */ + int err; + + data.id = id; + data.lower_inode = lower_inode; + inode = iget5_locked(sb, /* our superblock */ + /* + * hashval: we use inode number, but we can + * also use "(unsigned long)lower_inode" + * instead. + */ + lower_inode->i_ino, /* hashval */ + sdcardfs_inode_test, /* inode comparison function */ + sdcardfs_inode_set, /* inode init function */ + &data); /* data passed to test+set fxns */ + if (!inode) { + err = -EACCES; + iput(lower_inode); + return ERR_PTR(err); + } + /* if found a cached inode, then just return it */ + if (!(inode->i_state & I_NEW)) + return inode; + + /* initialize new inode */ + info = SDCARDFS_I(inode); + + inode->i_ino = lower_inode->i_ino; + if (!igrab(lower_inode)) { + err = -ESTALE; + return ERR_PTR(err); + } + sdcardfs_set_lower_inode(inode, lower_inode); + + inode->i_version++; + + /* use different set of inode ops for symlinks & directories */ + if (S_ISDIR(lower_inode->i_mode)) + inode->i_op = &sdcardfs_dir_iops; + else if (S_ISLNK(lower_inode->i_mode)) + inode->i_op = &sdcardfs_symlink_iops; + else + inode->i_op = &sdcardfs_main_iops; + + /* use different set of file ops for directories */ + if (S_ISDIR(lower_inode->i_mode)) + inode->i_fop = &sdcardfs_dir_fops; + else + inode->i_fop = &sdcardfs_main_fops; + + inode->i_mapping->a_ops = &sdcardfs_aops; + + inode->i_atime.tv_sec = 0; + inode->i_atime.tv_nsec = 0; + inode->i_mtime.tv_sec = 0; + inode->i_mtime.tv_nsec = 0; + inode->i_ctime.tv_sec = 0; + inode->i_ctime.tv_nsec = 0; + + /* properly initialize special inodes */ + if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) || + S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode)) + init_special_inode(inode, lower_inode->i_mode, + lower_inode->i_rdev); + + /* all well, copy inode attributes */ + sdcardfs_copy_and_fix_attrs(inode, lower_inode); + fsstack_copy_inode_size(inode, lower_inode); + + unlock_new_inode(inode); + return inode; +} + +/* + * Connect a sdcardfs inode dentry/inode with several lower ones. This is + * the classic stackable file system "vnode interposition" action. + * + * @dentry: sdcardfs's dentry which interposes on lower one + * @sb: sdcardfs's super_block + * @lower_path: the lower path (caller does path_get/put) + */ +int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb, + struct path *lower_path, userid_t id) +{ + int err = 0; + struct inode *inode; + struct inode *lower_inode; + struct super_block *lower_sb; + + lower_inode = d_inode(lower_path->dentry); + lower_sb = sdcardfs_lower_super(sb); + + /* check that the lower file system didn't cross a mount point */ + if (lower_inode->i_sb != lower_sb) { + err = -EXDEV; + goto out; + } + + /* + * We allocate our new inode below by calling sdcardfs_iget, + * which will initialize some of the new inode's fields + */ + + /* inherit lower inode number for sdcardfs's inode */ + inode = sdcardfs_iget(sb, lower_inode, id); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto out; + } + + d_add(dentry, inode); + update_derived_permission_lock(dentry); +out: + return err; +} + +/* + * Main driver function for sdcardfs's lookup. + * + * Returns: NULL (ok), ERR_PTR if an error occurred. + * Fills in lower_parent_path with <dentry,mnt> on success. + */ +static struct dentry *__sdcardfs_lookup(struct dentry *dentry, + unsigned int flags, struct path *lower_parent_path, userid_t id) +{ + int err = 0; + struct vfsmount *lower_dir_mnt; + struct dentry *lower_dir_dentry = NULL; + struct dentry *lower_dentry; + const char *name; + struct path lower_path; + struct qstr this; + struct sdcardfs_sb_info *sbi; + + sbi = SDCARDFS_SB(dentry->d_sb); + /* must initialize dentry operations */ + d_set_d_op(dentry, &sdcardfs_ci_dops); + + if (IS_ROOT(dentry)) + goto out; + + name = dentry->d_name.name; + + /* now start the actual lookup procedure */ + lower_dir_dentry = lower_parent_path->dentry; + lower_dir_mnt = lower_parent_path->mnt; + + /* Use vfs_path_lookup to check if the dentry exists or not */ + err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name, 0, + &lower_path); + /* check for other cases */ + if (err == -ENOENT) { + struct dentry *child; + struct dentry *match = NULL; + inode_lock(d_inode(lower_dir_dentry)); + spin_lock(&lower_dir_dentry->d_lock); + list_for_each_entry(child, &lower_dir_dentry->d_subdirs, d_child) { + if (child && d_inode(child)) { + if (strcasecmp(child->d_name.name, name)==0) { + match = dget(child); + break; + } + } + } + spin_unlock(&lower_dir_dentry->d_lock); + inode_unlock(d_inode(lower_dir_dentry)); + if (match) { + err = vfs_path_lookup(lower_dir_dentry, + lower_dir_mnt, + match->d_name.name, 0, + &lower_path); + dput(match); + } + } + + /* no error: handle positive dentries */ + if (!err) { + /* check if the dentry is an obb dentry + * if true, the lower_inode must be replaced with + * the inode of the graft path */ + + if(need_graft_path(dentry)) { + + /* setup_obb_dentry() + * The lower_path will be stored to the dentry's orig_path + * and the base obbpath will be copyed to the lower_path variable. + * if an error returned, there's no change in the lower_path + * returns: -ERRNO if error (0: no error) */ + err = setup_obb_dentry(dentry, &lower_path); + + if(err) { + /* if the sbi->obbpath is not available, we can optionally + * setup the lower_path with its orig_path. + * but, the current implementation just returns an error + * because the sdcard daemon also regards this case as + * a lookup fail. */ + printk(KERN_INFO "sdcardfs: base obbpath is not available\n"); + sdcardfs_put_reset_orig_path(dentry); + goto out; + } + } + + sdcardfs_set_lower_path(dentry, &lower_path); + err = sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id); + if (err) /* path_put underlying path on error */ + sdcardfs_put_reset_lower_path(dentry); + goto out; + } + + /* + * We don't consider ENOENT an error, and we want to return a + * negative dentry. + */ + if (err && err != -ENOENT) + goto out; + + /* instatiate a new negative dentry */ + this.name = name; + this.len = strlen(name); + this.hash = full_name_hash(dentry, this.name, this.len); + lower_dentry = d_lookup(lower_dir_dentry, &this); + if (lower_dentry) + goto setup_lower; + + lower_dentry = d_alloc(lower_dir_dentry, &this); + if (!lower_dentry) { + err = -ENOMEM; + goto out; + } + d_add(lower_dentry, NULL); /* instantiate and hash */ + +setup_lower: + lower_path.dentry = lower_dentry; + lower_path.mnt = mntget(lower_dir_mnt); + sdcardfs_set_lower_path(dentry, &lower_path); + + /* + * If the intent is to create a file, then don't return an error, so + * the VFS will continue the process of making this negative dentry + * into a positive one. + */ + if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET)) + err = 0; + +out: + return ERR_PTR(err); +} + +/* + * On success: + * fills dentry object appropriate values and returns NULL. + * On fail (== error) + * returns error ptr + * + * @dir : Parent inode. + * @dentry : Target dentry to lookup. we should set each of fields. + * (dentry->d_name is initialized already) + * @nd : nameidata of parent inode + */ +struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + struct dentry *ret = NULL, *parent; + struct path lower_parent_path; + int err = 0; + const struct cred *saved_cred = NULL; + + parent = dget_parent(dentry); + + if(!check_caller_access_to_name(d_inode(parent), dentry->d_name.name)) { + ret = ERR_PTR(-EACCES); + printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" + " dentry: %s, task:%s\n", + __func__, dentry->d_name.name, current->comm); + goto out_err; + } + + /* save current_cred and override it */ + OVERRIDE_CRED_PTR(SDCARDFS_SB(dir->i_sb), saved_cred); + + sdcardfs_get_lower_path(parent, &lower_parent_path); + + /* allocate dentry private data. We free it in ->d_release */ + err = new_dentry_private_data(dentry); + if (err) { + ret = ERR_PTR(err); + goto out; + } + + ret = __sdcardfs_lookup(dentry, flags, &lower_parent_path, SDCARDFS_I(dir)->userid); + if (IS_ERR(ret)) + { + goto out; + } + if (ret) + dentry = ret; + if (d_inode(dentry)) { + fsstack_copy_attr_times(d_inode(dentry), + sdcardfs_lower_inode(d_inode(dentry))); + /* get derived permission */ + get_derived_permission(parent, dentry); + fixup_tmp_permissions(d_inode(dentry)); + } + /* update parent directory's atime */ + fsstack_copy_attr_atime(d_inode(parent), + sdcardfs_lower_inode(d_inode(parent))); + +out: + sdcardfs_put_lower_path(parent, &lower_parent_path); + REVERT_CRED(saved_cred); +out_err: + dput(parent); + return ret; +} |