From 8665bd53f2f2e27e5511d90428cb3f60e6d0ce15 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 18 May 2024 20:50:12 +0200 Subject: Merging upstream version 6.8.9. Signed-off-by: Daniel Baumann --- fs/bcachefs/dirent_format.h | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 fs/bcachefs/dirent_format.h (limited to 'fs/bcachefs/dirent_format.h') diff --git a/fs/bcachefs/dirent_format.h b/fs/bcachefs/dirent_format.h new file mode 100644 index 0000000000..5e116b88e8 --- /dev/null +++ b/fs/bcachefs/dirent_format.h @@ -0,0 +1,42 @@ +/* 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 */ -- cgit v1.2.3