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ext4: support GETFSMAP ioctls

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Support the GETFSMAP ioctls so that we can use the xfs free space
management tools to probe ext4 as well.  Note that this is a partial
implementation -- we only report fixed-location metadata and free space;
everything else is reported as "unknown".

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong
2017-04-30 00:36:53 -04:00
committed by Theodore Ts'o
parent d0649f0416
commit 0c9ec4beec
8 changed files with 1027 additions and 5 deletions
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90
fs/ext4/ioctl.c
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@@ -19,6 +19,9 @@
#include <linux/delay.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include <linux/fsmap.h>
#include "fsmap.h"
#include <trace/events/ext4.h>
/**
* Swap memory between @a and @b for @len bytes.
@@ -489,6 +492,90 @@ int ext4_shutdown(struct super_block *sb, unsigned long arg)
return 0;
}
struct getfsmap_info {
struct super_block *gi_sb;
struct fsmap_head __user *gi_data;
unsigned int gi_idx;
__u32 gi_last_flags;
};
static int ext4_getfsmap_format(struct ext4_fsmap *xfm, void *priv)
{
struct getfsmap_info *info = priv;
struct fsmap fm;
trace_ext4_getfsmap_mapping(info->gi_sb, xfm);
info->gi_last_flags = xfm->fmr_flags;
ext4_fsmap_from_internal(info->gi_sb, &fm, xfm);
if (copy_to_user(&info->gi_data->fmh_recs[info->gi_idx++], &fm,
sizeof(struct fsmap)))
return -EFAULT;
return 0;
}
static int ext4_ioc_getfsmap(struct super_block *sb,
struct fsmap_head __user *arg)
{
struct getfsmap_info info = {0};
struct ext4_fsmap_head xhead = {0};
struct fsmap_head head;
bool aborted = false;
int error;
if (copy_from_user(&head, arg, sizeof(struct fsmap_head)))
return -EFAULT;
if (memchr_inv(head.fmh_reserved, 0, sizeof(head.fmh_reserved)) ||
memchr_inv(head.fmh_keys[0].fmr_reserved, 0,
sizeof(head.fmh_keys[0].fmr_reserved)) ||
memchr_inv(head.fmh_keys[1].fmr_reserved, 0,
sizeof(head.fmh_keys[1].fmr_reserved)))
return -EINVAL;
/*
* ext4 doesn't report file extents at all, so the only valid
* file offsets are the magic ones (all zeroes or all ones).
*/
if (head.fmh_keys[0].fmr_offset ||
(head.fmh_keys[1].fmr_offset != 0 &&
head.fmh_keys[1].fmr_offset != -1ULL))
return -EINVAL;
xhead.fmh_iflags = head.fmh_iflags;
xhead.fmh_count = head.fmh_count;
ext4_fsmap_to_internal(sb, &xhead.fmh_keys[0], &head.fmh_keys[0]);
ext4_fsmap_to_internal(sb, &xhead.fmh_keys[1], &head.fmh_keys[1]);
trace_ext4_getfsmap_low_key(sb, &xhead.fmh_keys[0]);
trace_ext4_getfsmap_high_key(sb, &xhead.fmh_keys[1]);
info.gi_sb = sb;
info.gi_data = arg;
error = ext4_getfsmap(sb, &xhead, ext4_getfsmap_format, &info);
if (error == EXT4_QUERY_RANGE_ABORT) {
error = 0;
aborted = true;
} else if (error)
return error;
/* If we didn't abort, set the "last" flag in the last fmx */
if (!aborted && info.gi_idx) {
info.gi_last_flags |= FMR_OF_LAST;
if (copy_to_user(&info.gi_data->fmh_recs[info.gi_idx - 1].fmr_flags,
&info.gi_last_flags,
sizeof(info.gi_last_flags)))
return -EFAULT;
}
/* copy back header */
head.fmh_entries = xhead.fmh_entries;
head.fmh_oflags = xhead.fmh_oflags;
if (copy_to_user(arg, &head, sizeof(struct fsmap_head)))
return -EFAULT;
return 0;
}
long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -499,6 +586,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
ext4_debug("cmd = %u, arg = %lu\n", cmd, arg);
switch (cmd) {
case FS_IOC_GETFSMAP:
return ext4_ioc_getfsmap(sb, (void __user *)arg);
case EXT4_IOC_GETFLAGS:
ext4_get_inode_flags(ei);
flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
@@ -1009,6 +1098,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case EXT4_IOC_GET_ENCRYPTION_PWSALT:
case EXT4_IOC_GET_ENCRYPTION_POLICY:
case EXT4_IOC_SHUTDOWN:
case FS_IOC_GETFSMAP:
break;
default:
return -ENOIOCTLCMD;