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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_DIRENT_FORMAT_H
#define _BCACHEFS_DIRENT_FORMAT_H
/*
* Dirents (and xattrs) have to implement string lookups; since our b-tree
* doesn't support arbitrary length strings for the key, we instead index by a
* 64 bit hash (currently truncated sha1) of the string, stored in the offset
* field of the key - using linear probing to resolve hash collisions. This also
* provides us with the readdir cookie posix requires.
*
* Linear probing requires us to use whiteouts for deletions, in the event of a
* collision:
*/
struct bch_dirent {
struct bch_val v;
/* Target inode number: */
union {
__le64 d_inum;
struct { /* DT_SUBVOL */
__le32 d_child_subvol;
__le32 d_parent_subvol;
};
};
/*
* Copy of mode bits 12-15 from the target inode - so userspace can get
* the filetype without having to do a stat()
*/
__u8 d_type;
__u8 d_name[];
} __packed __aligned(8);
#define DT_SUBVOL 16
#define BCH_DT_MAX 17
#define BCH_NAME_MAX 512
#endif /* _BCACHEFS_DIRENT_FORMAT_H */
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