From: Arnd Bergmann <arnd@arndb.de>
To: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
linux-afs@lists.infradead.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 32/32] [RFC] fsinfo: Add a system call to allow querying of filesystem information [ver #8]
Date: Mon, 4 Jun 2018 15:10:18 +0200 [thread overview]
Message-ID: <CAK8P3a0rO=F_n0pmsxUghRrF9hC_2+2Bd6RaVwC9H-=Xo6oQWA@mail.gmail.com> (raw)
In-Reply-To: <152720693123.9073.4511934790831409009.stgit@warthog.procyon.org.uk>
On Fri, May 25, 2018 at 2:08 AM, David Howells <dhowells@redhat.com> wrote:
> +
> +static int fsinfo_generic_timestamp_info(struct dentry *dentry,
> + struct fsinfo_timestamp_info *ts)
> +{
> + struct super_block *sb = dentry->d_sb;
> +
> + /* If unset, assume 1s granularity */
> + u16 mantissa = 1;
> + s8 exponent = 0;
> +
> + ts->minimum_timestamp = S64_MIN;
> + ts->maximum_timestamp = S64_MAX;
> + if (sb->s_time_gran < 1000000000) {
> + if (sb->s_time_gran < 1000)
> + exponent = -9;
> + else if (sb->s_time_gran < 1000000)
> + exponent = -6;
> + else
> + exponent = -3;
> + }
ntfs has sb->s_time_gran=100, and vfat should really have
sb->s_time_gran=2000000000 but that doesn't seem to be set right
at the moment.
> +/*
> + * Optional fsinfo() parameter structure.
> + *
> + * If this is not given, it is assumed that fsinfo_attr_statfs instance 0 is
> + * desired.
> + */
> +struct fsinfo_params {
> + enum fsinfo_attribute request; /* What is being asking for */
> + __u32 Nth; /* Instance of it (some may have multiple) */
> + __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
> + __u32 __spare[6]; /* Spare params; all must be 0 */
> +};
I fear the 'enum' in the uapi structure may have a different size depending
on the architecture. Maybe turn that into a __u32 as well?
> +struct fsinfo_capabilities {
> + __u64 supported_stx_attributes; /* What statx::stx_attributes are supported */
> + __u32 supported_stx_mask; /* What statx::stx_mask bits are supported */
> + __u32 supported_ioc_flags; /* What FS_IOC_* flags are supported */
> + __u8 capabilities[(fsinfo_cap__nr + 7) / 8];
> +};
This looks a bit odd: with the 44 capabilities, you end up having a
six-byte array
followed by two bytes of implicit padding. If the number of
capabilities grows beyond
64, you have a nine byte array with more padding to the next alignof(__u64). Is
that intentional?
How about making it a fixed size with either 64 or 128 capability bits?
> +/*
> + * Information struct for fsinfo(fsinfo_attr_timestamp_info).
> + */
> +struct fsinfo_timestamp_info {
> + __s64 minimum_timestamp; /* Minimum timestamp value in seconds */
> + __s64 maximum_timestamp; /* Maximum timestamp value in seconds */
> + __u16 atime_gran_mantissa; /* Granularity(secs) = mant * 10^exp */
> + __u16 btime_gran_mantissa;
> + __u16 ctime_gran_mantissa;
> + __u16 mtime_gran_mantissa;
> + __s8 atime_gran_exponent;
> + __s8 btime_gran_exponent;
> + __s8 ctime_gran_exponent;
> + __s8 mtime_gran_exponent;
> +};
This structure has a slightly inconsistent amount of padding at the end:
on x86-32 it has no padding, everywhere else it has 32 bits of padding
to make it 64-bit aligned. Maybe add a __u32 reserved field?
> +
> +#define __NR_fsinfo 326
Hardcoding the syscall number in the example makes it architecture specific.
Could you include <asm/unistd.h> to get the real number?
Arnd
next prev parent reply other threads:[~2018-06-04 13:10 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-25 0:05 [PATCH 00/32] VFS: Introduce filesystem context [ver #8] David Howells
2018-05-25 0:05 ` [PATCH 01/32] VFS: Suppress MS_* flag defs within the kernel unless explicitly enabled " David Howells
2018-05-25 0:05 ` [PATCH 02/32] vfs: Provide documentation for new mount API " David Howells
2018-05-25 0:05 ` [PATCH 03/32] VFS: Introduce the basic header for the new mount API's filesystem context " David Howells
2018-05-31 23:11 ` Al Viro
2018-05-31 23:13 ` Al Viro
2018-05-25 0:05 ` [PATCH 04/32] VFS: Add LSM hooks for the new mount API " David Howells
2018-05-25 0:05 ` [PATCH 05/32] selinux: Implement the new mount API LSM hooks " David Howells
2018-05-25 0:06 ` [PATCH 06/32] smack: Implement filesystem context security " David Howells
2018-05-25 0:06 ` [PATCH 07/32] apparmor: Implement security hooks for the new mount API " David Howells
2018-05-25 0:06 ` [PATCH 08/32] tomoyo: " David Howells
2018-05-25 0:06 ` [PATCH 09/32] VFS: Require specification of size of mount data for internal mounts " David Howells
2018-05-25 0:06 ` [PATCH 10/32] VFS: Implement a filesystem superblock creation/configuration context " David Howells
2018-06-07 19:50 ` Miklos Szeredi
2018-07-03 18:33 ` Eric Biggers
2018-07-03 21:53 ` David Howells
2018-07-03 21:58 ` Al Viro
2018-07-03 22:06 ` David Howells
2018-05-25 0:06 ` [PATCH 11/32] VFS: Remove unused code after filesystem context changes " David Howells
2018-05-25 0:06 ` [PATCH 12/32] procfs: Move proc_fill_super() to fs/proc/root.c " David Howells
2018-05-25 0:06 ` [PATCH 13/32] proc: Add fs_context support to procfs " David Howells
2018-05-25 0:06 ` [PATCH 14/32] ipc: Convert mqueue fs to fs_context " David Howells
2018-05-25 0:07 ` [PATCH 15/32] cpuset: Use " David Howells
2018-05-25 0:07 ` [PATCH 16/32] kernfs, sysfs, cgroup, intel_rdt: Support " David Howells
2018-06-21 18:47 ` [16/32] " Andrei Vagin
2018-06-22 12:52 ` David Howells
2018-06-22 15:30 ` Andrei Vagin
2018-06-22 16:57 ` Andrei Vagin
2018-06-23 23:34 ` David Howells
2018-05-25 0:07 ` [PATCH 17/32] hugetlbfs: Convert to " David Howells
2018-05-25 0:07 ` [PATCH 18/32] VFS: Remove kern_mount_data() " David Howells
2018-05-25 0:07 ` [PATCH 19/32] VFS: Implement fsopen() to prepare for a mount " David Howells
2018-05-31 21:25 ` Al Viro
2018-05-25 0:07 ` [PATCH 20/32] vfs: Make close() unmount the attached mount if so flagged " David Howells
2018-05-31 19:19 ` Al Viro
2018-05-31 19:26 ` Al Viro
2018-06-01 1:52 ` Al Viro
2018-06-01 3:18 ` Al Viro
2018-06-01 5:16 ` Al Viro
2018-05-25 0:07 ` [PATCH 21/32] VFS: Implement fsmount() to effect a pre-configured mount " David Howells
2018-06-04 15:05 ` Arnd Bergmann
2018-06-04 15:24 ` David Howells
2018-05-25 0:07 ` [PATCH 22/32] vfs: Provide an fspick() system call " David Howells
2018-05-25 0:07 ` [PATCH 23/32] VFS: Implement logging through fs_context " David Howells
2018-05-25 1:48 ` Joe Perches
2018-05-25 0:07 ` [PATCH 24/32] vfs: Add some logging to the core users of the fs_context log " David Howells
2018-05-25 0:08 ` [PATCH 25/32] afs: Add fs_context support " David Howells
2018-05-25 0:08 ` [PATCH 26/32] afs: Use fs_context to pass parameters over automount " David Howells
2018-06-07 1:58 ` Goldwyn Rodrigues
2018-06-07 20:45 ` David Howells
2018-05-25 0:08 ` [PATCH 27/32] vfs: Use a 'struct fd_cookie *' type for light fd handling " David Howells
2018-05-25 0:08 ` [PATCH 28/32] vfs: Store the fd_cookie in nameidata, not the dfd int " David Howells
2018-05-25 0:08 ` [PATCH 29/32] vfs: Don't mix FMODE_* flags with O_* flags " David Howells
2018-05-25 0:08 ` [PATCH 30/32] vfs: Allow cloning of a mount tree with open(O_PATH|O_CLONE_MOUNT) " David Howells
2018-06-01 6:26 ` Christoph Hellwig
2018-06-01 6:39 ` Al Viro
2018-06-01 8:27 ` David Howells
2018-06-02 3:09 ` Al Viro
2018-06-02 3:42 ` Al Viro
2018-06-02 4:04 ` Al Viro
2018-06-02 15:45 ` David Howells
2018-06-02 17:49 ` Al Viro
2018-06-03 0:55 ` [PATCH][RFC] open_tree(2) (was Re: [PATCH 30/32] vfs: Allow cloning of a mount tree with open(O_PATH|O_CLONE_MOUNT) [ver #8]) Al Viro
2018-06-04 10:34 ` Miklos Szeredi
2018-06-04 15:52 ` Al Viro
2018-06-04 15:59 ` Al Viro
2018-06-04 19:27 ` Miklos Szeredi
2018-06-04 15:27 ` David Howells
2018-06-04 17:16 ` Matthew Wilcox
2018-06-04 17:35 ` Al Viro
2018-06-04 19:38 ` Miklos Szeredi
2018-06-01 8:02 ` [PATCH 30/32] vfs: Allow cloning of a mount tree with open(O_PATH|O_CLONE_MOUNT) [ver #8] Amir Goldstein
2018-06-01 8:42 ` David Howells
2018-05-25 0:08 ` [PATCH 31/32] [RFC] fs: Add a move_mount() system call " David Howells
2018-05-31 21:20 ` Al Viro
2018-05-25 0:08 ` [PATCH 32/32] [RFC] fsinfo: Add a system call to allow querying of filesystem information " David Howells
2018-06-04 13:10 ` Arnd Bergmann [this message]
2018-06-04 15:01 ` David Howells
2018-06-04 16:00 ` Arnd Bergmann
2018-06-04 19:03 ` David Howells
2018-06-04 20:45 ` Arnd Bergmann
2018-05-31 20:56 ` Test program for move_mount() David Howells
2018-05-31 20:57 ` fsinfo test program David Howells
2018-06-15 4:18 ` [PATCH 00/32] VFS: Introduce filesystem context [ver #8] Eric W. Biederman
2018-06-18 20:30 ` David Howells
2018-06-18 21:33 ` Eric W. Biederman
2018-06-18 23:33 ` Theodore Y. Ts'o
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