From bd42998a6bcb9b1708dac9ca9876e3d304c16f3d Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 1 Apr 2014 17:08:44 +0200 Subject: [PATCH] ext4: add cross rename support Implement RENAME_EXCHANGE flag in renameat2 syscall. Signed-off-by: Miklos Szeredi Reviewed-by: Jan Kara --- fs/ext4/namei.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 138 insertions(+), 1 deletion(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 75f1bde43dcc..1cb84f78909e 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3004,6 +3004,8 @@ struct ext4_renament { struct inode *dir; struct dentry *dentry; struct inode *inode; + bool is_dir; + int dir_nlink_delta; /* entry for "dentry" */ struct buffer_head *bh; @@ -3135,6 +3137,17 @@ static void ext4_rename_delete(handle_t *handle, struct ext4_renament *ent) } } +static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent) +{ + if (ent->dir_nlink_delta) { + if (ent->dir_nlink_delta == -1) + ext4_dec_count(handle, ent->dir); + else + ext4_inc_count(handle, ent->dir); + ext4_mark_inode_dirty(handle, ent->dir); + } +} + /* * Anybody can rename anything with this: the permission checks are left to the * higher-level routines. @@ -3274,13 +3287,137 @@ end_rename: return retval; } +static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + handle_t *handle = NULL; + struct ext4_renament old = { + .dir = old_dir, + .dentry = old_dentry, + .inode = old_dentry->d_inode, + }; + struct ext4_renament new = { + .dir = new_dir, + .dentry = new_dentry, + .inode = new_dentry->d_inode, + }; + u8 new_file_type; + int retval; + + dquot_initialize(old.dir); + dquot_initialize(new.dir); + + old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, + &old.de, &old.inlined); + /* + * Check for inode number is _not_ due to possible IO errors. + * We might rmdir the source, keep it as pwd of some process + * and merrily kill the link to whatever was created under the + * same name. Goodbye sticky bit ;-< + */ + retval = -ENOENT; + if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino) + goto end_rename; + + new.bh = ext4_find_entry(new.dir, &new.dentry->d_name, + &new.de, &new.inlined); + + /* RENAME_EXCHANGE case: old *and* new must both exist */ + if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino) + goto end_rename; + + handle = ext4_journal_start(old.dir, EXT4_HT_DIR, + (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) + + 2 * EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2)); + if (IS_ERR(handle)) + return PTR_ERR(handle); + + if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir)) + ext4_handle_sync(handle); + + if (S_ISDIR(old.inode->i_mode)) { + old.is_dir = true; + retval = ext4_rename_dir_prepare(handle, &old); + if (retval) + goto end_rename; + } + if (S_ISDIR(new.inode->i_mode)) { + new.is_dir = true; + retval = ext4_rename_dir_prepare(handle, &new); + if (retval) + goto end_rename; + } + + /* + * Other than the special case of overwriting a directory, parents' + * nlink only needs to be modified if this is a cross directory rename. + */ + if (old.dir != new.dir && old.is_dir != new.is_dir) { + old.dir_nlink_delta = old.is_dir ? -1 : 1; + new.dir_nlink_delta = -old.dir_nlink_delta; + retval = -EMLINK; + if ((old.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(old.dir)) || + (new.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(new.dir))) + goto end_rename; + } + + new_file_type = new.de->file_type; + retval = ext4_setent(handle, &new, old.inode->i_ino, old.de->file_type); + if (retval) + goto end_rename; + + retval = ext4_setent(handle, &old, new.inode->i_ino, new_file_type); + if (retval) + goto end_rename; + + /* + * Like most other Unix systems, set the ctime for inodes on a + * rename. + */ + old.inode->i_ctime = ext4_current_time(old.inode); + new.inode->i_ctime = ext4_current_time(new.inode); + ext4_mark_inode_dirty(handle, old.inode); + ext4_mark_inode_dirty(handle, new.inode); + + if (old.dir_bh) { + retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino); + if (retval) + goto end_rename; + } + if (new.dir_bh) { + retval = ext4_rename_dir_finish(handle, &new, old.dir->i_ino); + if (retval) + goto end_rename; + } + ext4_update_dir_count(handle, &old); + ext4_update_dir_count(handle, &new); + retval = 0; + +end_rename: + brelse(old.dir_bh); + brelse(new.dir_bh); + brelse(old.bh); + brelse(new.bh); + if (handle) + ext4_journal_stop(handle); + return retval; +} + static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) { - if (flags & ~RENAME_NOREPLACE) + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) return -EINVAL; + if (flags & RENAME_EXCHANGE) { + return ext4_cross_rename(old_dir, old_dentry, + new_dir, new_dentry); + } + /* + * Existence checking was done by the VFS, otherwise "RENAME_NOREPLACE" + * is equivalent to regular rename. + */ return ext4_rename(old_dir, old_dentry, new_dir, new_dentry); } -- 2.39.2