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Commit 46fdb794 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

shmem: support RENAME_WHITEOUT 



Allocate a dentry, initialize it with a whiteout and hash it in the place
of the old dentry.  Later the old dentry will be moved away and the
whiteout will remain.

i_mutex protects agains concurrent readdir.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
parent cd808dec

mm/shmem.c

+35 −1
Original line number Diff line number Diff line
@@ -2345,6 +2345,32 @@ static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, stru 
	return 0;

}



static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)

{

	struct dentry *whiteout;

	int error;



	whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);

	if (!whiteout)

		return -ENOMEM;



	error = shmem_mknod(old_dir, whiteout,

			    S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);

	dput(whiteout);

	if (error)

		return error;



	/*

	 * Cheat and hash the whiteout while the old dentry is still in

	 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.

	 *

	 * d_lookup() will consistently find one of them at this point,

	 * not sure which one, but that isn't even important.

	 */

	d_rehash(whiteout);

	return 0;

}



/*

 * The VFS layer already does all the dentry stuff for rename,

 * we just have to decrement the usage count for the target if
@@ -2356,7 +2382,7 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc 
	struct inode *inode = old_dentry->d_inode;

	int they_are_dirs = S_ISDIR(inode->i_mode);



	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))

	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))

		return -EINVAL;



	if (flags & RENAME_EXCHANGE)
@@ -2365,6 +2391,14 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc 
	if (!simple_empty(new_dentry))

		return -ENOTEMPTY;



	if (flags & RENAME_WHITEOUT) {

		int error;



		error = shmem_whiteout(old_dir, old_dentry);

		if (error)

			return error;

	}



	if (new_dentry->d_inode) {

		(void) shmem_unlink(new_dir, new_dentry);

		if (they_are_dirs) {