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Date: Tue, 11 Feb 2014 22:23:46 +0100
From: Jan Kara <jack@...e.cz>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: viro@...IV.linux.org.uk, torvalds@...ux-foundation.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
bfields@...ldses.org, hch@...radead.org, akpm@...ux-foundation.org,
dhowells@...hat.com, zab@...hat.com, jack@...e.cz,
luto@...capital.net, mszeredi@...e.cz
Subject: Re: [PATCH 12/13] ext4: add cross rename support
On Fri 07-02-14 17:49:10, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@...e.cz>
>
> Implement RENAME_EXCHANGE flag in renameat2 syscall.
Hum, I guess the nice symmetry of ext4_cross_rename() outweights the code
duplication. So you can add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
>
> Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> ---
> 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);
> }
>
> --
> 1.8.1.4
>
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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