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fs: introduce file_getattr and file_setattr syscalls

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Introduce file_getattr() and file_setattr() syscalls to manipulate inode
extended attributes. The syscalls takes pair of file descriptor and
pathname. Then it operates on inode opened accroding to openat()
semantics. The struct file_attr is passed to obtain/change extended
attributes.

This is an alternative to FS_IOC_FSSETXATTR ioctl with a difference
that file don't need to be open as we can reference it with a path
instead of fd. By having this we can manipulated inode extended
attributes not only on regular files but also on special ones. This
is not possible with FS_IOC_FSSETXATTR ioctl as with special files
we can not call ioctl() directly on the filesystem inode using fd.

This patch adds two new syscalls which allows userspace to get/set
extended inode attributes on special files by using parent directory
and a path - *at() like syscall.

CC: linux-api@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: linux-xfs@vger.kernel.org
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-6-c4e3bc35227b@kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Andrey Albershteyn
2025-07-02 17:05:17 +02:00
committed by Christian Brauner
parent 276e136bff
commit be7efb2d20
21 changed files with 218 additions and 1 deletions
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include/uapi/asm-generic/unistd.h
+7 -1
View File
@@ -852,8 +852,14 @@ __SYSCALL(__NR_removexattrat, sys_removexattrat)
#define __NR_open_tree_attr 467
__SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
/* fs/inode.c */
#define __NR_file_getattr 468
__SYSCALL(__NR_file_getattr, sys_file_getattr)
#define __NR_file_setattr 469
__SYSCALL(__NR_file_setattr, sys_file_setattr)
#undef __NR_syscalls
#define __NR_syscalls 468
#define __NR_syscalls 470
/*
* 32 bit systems traditionally used different
include/uapi/linux/fs.h
+18
View File
@@ -148,6 +148,24 @@ struct fsxattr {
unsigned char fsx_pad[8];
};
/*
* Variable size structure for file_[sg]et_attr().
*
* Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
* As this structure is passed to/from userspace with its size, this can
* be versioned based on the size.
*/
struct file_attr {
__u64 fa_xflags; /* xflags field value (get/set) */
__u32 fa_extsize; /* extsize field value (get/set)*/
__u32 fa_nextents; /* nextents field value (get) */
__u32 fa_projid; /* project identifier (get/set) */
__u32 fa_cowextsize; /* CoW extsize field value (get/set) */
};
#define FILE_ATTR_SIZE_VER0 24
#define FILE_ATTR_SIZE_LATEST FILE_ATTR_SIZE_VER0
/*
* Flags for the fsx_xflags field
*/