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Message-ID: <20200219170421.GD9496@magnolia>
Date: Wed, 19 Feb 2020 09:04:21 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: David Howells <dhowells@...hat.com>
Cc: viro@...iv.linux.org.uk, raven@...maw.net, mszeredi@...hat.com,
christian@...uner.io, linux-api@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 18/19] ext4: Add example fsinfo information [ver #16]
On Tue, Feb 18, 2020 at 05:07:14PM +0000, David Howells wrote:
> Add the ability to list some ext4 volume timestamps as an example.
>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: linux-ext4@...r.kernel.org
> ---
>
> fs/ext4/Makefile | 1 +
> fs/ext4/ext4.h | 9 +++++++++
> fs/ext4/fsinfo.c | 40 ++++++++++++++++++++++++++++++++++++++++
> fs/ext4/super.c | 1 +
> include/uapi/linux/fsinfo.h | 16 ++++++++++++++++
> samples/vfs/test-fsinfo.c | 35 +++++++++++++++++++++++++++++++++++
> 6 files changed, 102 insertions(+)
> create mode 100644 fs/ext4/fsinfo.c
>
> diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
> index 4ccb3c9189d8..71d5b460c7c7 100644
> --- a/fs/ext4/Makefile
> +++ b/fs/ext4/Makefile
> @@ -16,3 +16,4 @@ ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
> ext4-inode-test-objs += inode-test.o
> obj-$(CONFIG_EXT4_KUNIT_TESTS) += ext4-inode-test.o
> ext4-$(CONFIG_FS_VERITY) += verity.o
> +ext4-$(CONFIG_FSINFO) += fsinfo.o
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 9a2ee2428ecc..d81b04227da7 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -42,6 +42,7 @@
>
> #include <linux/fscrypt.h>
> #include <linux/fsverity.h>
> +#include <linux/fsinfo.h>
>
> #include <linux/compiler.h>
>
> @@ -3166,6 +3167,14 @@ extern const struct inode_operations ext4_file_inode_operations;
> extern const struct file_operations ext4_file_operations;
> extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
>
> +/* fsinfo.c */
> +#ifdef CONFIG_FSINFO
> +struct fsinfo_attribute;
> +extern const struct fsinfo_attribute ext4_fsinfo_attributes[];
> +#else
> +#define ext4_fsinfo_attributes NULL
> +#endif
> +
> /* inline.c */
> extern int ext4_get_max_inline_size(struct inode *inode);
> extern int ext4_find_inline_data_nolock(struct inode *inode);
> diff --git a/fs/ext4/fsinfo.c b/fs/ext4/fsinfo.c
> new file mode 100644
> index 000000000000..545424c410ff
> --- /dev/null
> +++ b/fs/ext4/fsinfo.c
> @@ -0,0 +1,40 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Filesystem information for ext4
> + *
> + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@...hat.com)
> + */
> +
> +#include <linux/mount.h>
> +#include "ext4.h"
> +
> +static int ext4_fsinfo_get_volume_name(struct path *path, struct fsinfo_context *ctx)
> +{
> + const struct ext4_sb_info *sbi = EXT4_SB(path->mnt->mnt_sb);
> + const struct ext4_super_block *es = sbi->s_es;
> +
> + memcpy(ctx->buffer, es->s_volume_name, sizeof(es->s_volume_name));
Shouldn't this be checking that ctx->buffer is large enough to hold
s_volume_name?
> + return strlen(ctx->buffer);
s_volume_name is /not/ a null-terminated string if the label is 16
characters long.
> +}
> +
> +static int ext4_fsinfo_get_timestamps(struct path *path, struct fsinfo_context *ctx)
> +{
> + const struct ext4_sb_info *sbi = EXT4_SB(path->mnt->mnt_sb);
> + const struct ext4_super_block *es = sbi->s_es;
> + struct fsinfo_ext4_timestamps *ts = ctx->buffer;
> +
> +#define Z(R,S) R = S | (((u64)S##_hi) << 32)
> + Z(ts->mkfs_time, es->s_mkfs_time);
> + Z(ts->mount_time, es->s_mtime);
> + Z(ts->write_time, es->s_wtime);
> + Z(ts->last_check_time, es->s_lastcheck);
> + Z(ts->first_error_time, es->s_first_error_time);
> + Z(ts->last_error_time, es->s_last_error_time);
> + return sizeof(*ts);
> +}
> +
> +const struct fsinfo_attribute ext4_fsinfo_attributes[] = {
> + FSINFO_STRING (FSINFO_ATTR_VOLUME_NAME, ext4_fsinfo_get_volume_name),
> + FSINFO_VSTRUCT (FSINFO_ATTR_EXT4_TIMESTAMPS, ext4_fsinfo_get_timestamps),
> + {}
> +};
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 8434217549b3..e21c3d99747e 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1477,6 +1477,7 @@ static const struct super_operations ext4_sops = {
> .freeze_fs = ext4_freeze,
> .unfreeze_fs = ext4_unfreeze,
> .statfs = ext4_statfs,
> + .fsinfo_attributes = ext4_fsinfo_attributes,
> .remount_fs = ext4_remount,
> .show_options = ext4_show_options,
> #ifdef CONFIG_QUOTA
> diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
> index 5467f88ca9b0..da9a6f48ec5b 100644
> --- a/include/uapi/linux/fsinfo.h
> +++ b/include/uapi/linux/fsinfo.h
> @@ -38,6 +38,8 @@
> #define FSINFO_ATTR_AFS_SERVER_NAME 0x301 /* Name of the Nth server (string) */
> #define FSINFO_ATTR_AFS_SERVER_ADDRESSES 0x302 /* List of addresses of the Nth server */
>
> +#define FSINFO_ATTR_EXT4_TIMESTAMPS 0x400 /* Ext4 superblock timestamps */
I guess each filesystem gets ... 256 different attrs, and the third
nibble determines the namespace?
--D
> /*
> * Optional fsinfo() parameter structure.
> *
> @@ -323,4 +325,18 @@ struct fsinfo_afs_server_address {
>
> #define FSINFO_ATTR_AFS_SERVER_ADDRESSES__STRUCT struct fsinfo_afs_server_address
>
> +/*
> + * Information struct for fsinfo(FSINFO_ATTR_EXT4_TIMESTAMPS).
> + */
> +struct fsinfo_ext4_timestamps {
> + __u64 mkfs_time;
> + __u64 mount_time;
> + __u64 write_time;
> + __u64 last_check_time;
> + __u64 first_error_time;
> + __u64 last_error_time;
> +};
> +
> +#define FSINFO_ATTR_EXT4_TIMESTAMPS__STRUCT struct fsinfo_ext4_timestamps
> +
> #endif /* _UAPI_LINUX_FSINFO_H */
> diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
> index fd425c08b00b..53251ee98d1c 100644
> --- a/samples/vfs/test-fsinfo.c
> +++ b/samples/vfs/test-fsinfo.c
> @@ -359,6 +359,40 @@ static void dump_afs_fsinfo_server_address(void *reply, unsigned int size)
> printf("family=%u\n", ss->ss_family);
> }
>
> +static char *dump_ext4_time(char *buffer, time_t tim)
> +{
> + struct tm tm;
> + int len;
> +
> + if (tim == 0)
> + return "-";
> +
> + if (!localtime_r(&tim, &tm)) {
> + perror("localtime_r");
> + exit(1);
> + }
> + len = strftime(buffer, 100, "%F %T", &tm);
> + if (len == 0) {
> + perror("strftime");
> + exit(1);
> + }
> + return buffer;
> +}
> +
> +static void dump_ext4_fsinfo_timestamps(void *reply, unsigned int size)
> +{
> + struct fsinfo_ext4_timestamps *r = reply;
> + char buffer[100];
> +
> + printf("\n");
> + printf("\tmkfs : %s\n", dump_ext4_time(buffer, r->mkfs_time));
> + printf("\tmount : %s\n", dump_ext4_time(buffer, r->mount_time));
> + printf("\twrite : %s\n", dump_ext4_time(buffer, r->write_time));
> + printf("\tfsck : %s\n", dump_ext4_time(buffer, r->last_check_time));
> + printf("\t1st-err : %s\n", dump_ext4_time(buffer, r->first_error_time));
> + printf("\tlast-err: %s\n", dump_ext4_time(buffer, r->last_error_time));
> +}
> +
> static void dump_string(void *reply, unsigned int size)
> {
> char *s = reply, *p;
> @@ -433,6 +467,7 @@ static const struct fsinfo_attribute fsinfo_attributes[] = {
> FSINFO_STRING (FSINFO_ATTR_AFS_CELL_NAME, afs_cell_name),
> FSINFO_STRING (FSINFO_ATTR_AFS_SERVER_NAME, afs_server_name),
> FSINFO_LIST_N (FSINFO_ATTR_AFS_SERVER_ADDRESSES, afs_fsinfo_server_address),
> + FSINFO_VSTRUCT (FSINFO_ATTR_EXT4_TIMESTAMPS, ext4_fsinfo_timestamps),
> {}
> };
>
>
>
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