From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: "Jens Axboe" <axboe@kernel.dk>,
"Roger Pau Monné" <roger.pau@citrix.com>,
"Alasdair Kergon" <agk@redhat.com>,
"Mike Snitzer" <snitzer@kernel.org>,
dm-devel@redhat.com
Cc: "Demi Marie Obenour" <demi@invisiblethingslab.com>,
"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
xen-devel@lists.xenproject.org
Subject: [PATCH v2 12/16] device-mapper: inform caller about already-existing device
Date: Tue, 30 May 2023 16:31:12 -0400 [thread overview]
Message-ID: <20230530203116.2008-13-demi@invisiblethingslab.com> (raw)
In-Reply-To: <20230530203116.2008-1-demi@invisiblethingslab.com>
Not only is this helpful for debugging, it also saves the caller an
ioctl in the case where a device should be used if it exists or created
otherwise. To ensure existing userspace is not broken, this feature is
only enabled in strict mode.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
---
drivers/md/dm-ioctl.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 17ece816d490b6c40d019da131ade44c9a201dab..44425093d3b908abf80e05e1fc99a26b17e18a42 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -256,11 +256,13 @@ static void free_cell(struct hash_cell *hc)
}
}
+static void __dev_status(struct mapped_device *md, struct dm_ioctl *param);
+
/*
* The kdev_t and uuid of a device can never change once it is
* initially inserted.
*/
-static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
+static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md, struct dm_ioctl *param)
{
struct hash_cell *cell, *hc;
@@ -277,6 +279,8 @@ static int dm_hash_insert(const char *name, const char *uuid, struct mapped_devi
down_write(&_hash_lock);
hc = __get_name_cell(name);
if (hc) {
+ if (param)
+ __dev_status(hc->md, param);
dm_put(hc->md);
goto bad;
}
@@ -287,6 +291,8 @@ static int dm_hash_insert(const char *name, const char *uuid, struct mapped_devi
hc = __get_uuid_cell(uuid);
if (hc) {
__unlink_name(cell);
+ if (param)
+ __dev_status(hc->md, param);
dm_put(hc->md);
goto bad;
}
@@ -901,12 +907,14 @@ static int dev_create(struct file *filp, struct dm_ioctl *param, size_t param_si
m = MINOR(huge_decode_dev(param->dev));
r = dm_create(m, &md, param->flags & DM_DISABLE_UEVENTS_FLAG);
- if (r)
+ if (r) {
+ DMERR("Could not create device-mapper device");
return r;
+ }
param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
- r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
+ r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md, param);
if (r) {
dm_put(md);
dm_destroy(md);
@@ -2269,7 +2277,6 @@ static int ctl_ioctl(struct file *file, uint command, struct dm_ioctl __user *us
goto out;
/* This XOR keeps only the flags validate_params has changed. */
old_flags ^= param->flags;
-
param->data_size = sloppy_checks(param) ? offsetof(struct dm_ioctl, data) : sizeof(struct dm_ioctl);
r = fn(file, param, input_param_size);
@@ -2284,9 +2291,14 @@ static int ctl_ioctl(struct file *file, uint command, struct dm_ioctl __user *us
param->flags |= old_flags;
/*
- * Copy the results back to userland.
+ * Copy the results back to userland if either:
+ *
+ * - The ioctl succeeded.
+ * - The ioctl is DM_DEV_CREATE, the return value is -EBUSY,
+ * and strict parameter checking is enabled.
*/
- if (!r && copy_to_user(user, param, param->data_size))
+ if ((!r || (!sloppy_checks(param) && cmd == DM_DEV_CREATE_CMD && r == -EBUSY)) &&
+ copy_to_user(user, param, param->data_size))
r = -EFAULT;
out:
@@ -2465,7 +2477,7 @@ int __init dm_early_create(struct dm_ioctl *dmi,
return r;
/* hash insert */
- r = dm_hash_insert(dmi->name, *dmi->uuid ? dmi->uuid : NULL, md);
+ r = dm_hash_insert(dmi->name, *dmi->uuid ? dmi->uuid : NULL, md, NULL);
if (r)
goto err_destroy_dm;
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
next prev parent reply other threads:[~2023-05-30 20:33 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 20:31 [PATCH v2 00/16] Diskseq support in loop, device-mapper, and blkback Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 01/16] device-mapper: Check that target specs are sufficiently aligned Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 02/16] device-mapper: Avoid pointer arithmetic overflow Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 03/16] device-mapper: do not allow targets to overlap 'struct dm_ioctl' Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 04/16] device-mapper: Better error message for too-short target spec Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 05/16] device-mapper: Target parameters must not overlap next " Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 06/16] device-mapper: Avoid double-fetch of version Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 07/16] device-mapper: Allow userspace to opt-in to strict parameter checks Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 08/16] device-mapper: Allow userspace to provide expected diskseq Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 09/16] device-mapper: Allow userspace to suppress uevent generation Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 10/16] device-mapper: Refuse to create device named "control" Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 11/16] device-mapper: "." and ".." are not valid symlink names Demi Marie Obenour
2023-05-30 20:31 ` Demi Marie Obenour [this message]
2023-05-30 20:31 ` [PATCH v2 13/16] xen-blkback: Implement diskseq checks Demi Marie Obenour
2023-06-06 8:25 ` Roger Pau Monné
2023-06-06 17:01 ` Demi Marie Obenour
2023-06-07 8:20 ` Roger Pau Monné
2023-06-07 16:14 ` Demi Marie Obenour
2023-06-08 8:29 ` Roger Pau Monné
2023-06-08 15:33 ` Demi Marie Obenour
2023-06-09 15:13 ` Roger Pau Monné
2023-06-09 16:55 ` Demi Marie Obenour
2023-06-12 8:09 ` Roger Pau Monné
2023-06-21 1:14 ` Demi Marie Obenour
2023-06-21 10:07 ` Roger Pau Monné
2023-05-30 20:31 ` [PATCH v2 14/16] block, loop: Increment diskseq when releasing a loop device Demi Marie Obenour
2023-05-30 20:31 ` [PATCH v2 15/16] xen-blkback: Minor cleanups Demi Marie Obenour
2023-06-06 8:36 ` Roger Pau Monné
2023-05-30 20:31 ` [PATCH v2 16/16] xen-blkback: Inform userspace that device has been opened Demi Marie Obenour
2023-06-06 9:15 ` Roger Pau Monné
2023-06-06 17:31 ` Demi Marie Obenour
2023-06-07 8:44 ` Roger Pau Monné
2023-06-07 16:29 ` Demi Marie Obenour
2023-06-08 9:11 ` Roger Pau Monné
2023-06-08 15:23 ` Demi Marie Obenour
2023-06-08 10:08 ` Roger Pau Monné
2023-06-08 15:24 ` Demi Marie Obenour
2023-05-31 13:06 ` [dm-devel] [PATCH v2 00/16] Diskseq support in loop, device-mapper, and blkback Christoph Hellwig
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