fs: factor out vfs_parse_monolithic_sep() helper

Factor out vfs_parse_monolithic_sep() from generic_parse_monolithic(),
so filesystems could use it with a custom option separator callback.

Acked-by

fs: factor out vfs_parse_monolithic_sep() helper

Factor out vfs_parse_monolithic_sep() from generic_parse_monolithic(),
so filesystems could use it with a custom option separator callback.

Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

show more ...

fs: add FSCONFIG_CMD_CREATE_EXCL

Summary
=======

This introduces FSCONFIG_CMD_CREATE_EXCL which will allows userspace to
implement something like mount -t ext4 --exclusive /dev/sda /B which
fails i

fs: add FSCONFIG_CMD_CREATE_EXCL

Summary
=======

This introduces FSCONFIG_CMD_CREATE_EXCL which will allows userspace to
implement something like mount -t ext4 --exclusive /dev/sda /B which
fails if a superblock for the requested filesystem does already exist:

Before this patch
-----------------

$ sudo ./move-mount -f xfs -o source=/dev/sda4 /A
Requesting filesystem type xfs
Mount options requested: source=/dev/sda4
Attaching mount at /A
Moving single attached mount
Setting key(source) with val(/dev/sda4)

$ sudo ./move-mount -f xfs -o source=/dev/sda4 /B
Requesting filesystem type xfs
Mount options requested: source=/dev/sda4
Attaching mount at /B
Moving single attached mount
Setting key(source) with val(/dev/sda4)

After this patch with --exclusive as a switch for FSCONFIG_CMD_CREATE_EXCL
--------------------------------------------------------------------------

$ sudo ./move-mount -f xfs --exclusive -o source=/dev/sda4 /A
Requesting filesystem type xfs
Request exclusive superblock creation
Mount options requested: source=/dev/sda4
Attaching mount at /A
Moving single attached mount
Setting key(source) with val(/dev/sda4)

$ sudo ./move-mount -f xfs --exclusive -o source=/dev/sda4 /B
Requesting filesystem type xfs
Request exclusive superblock creation
Mount options requested: source=/dev/sda4
Attaching mount at /B
Moving single attached mount
Setting key(source) with val(/dev/sda4)
Device or resource busy | move-mount.c: 300: do_fsconfig: i xfs: reusing existing filesystem not allowed

Details
=======

As mentioned on the list (cf. [1]-[3]) mount requests like
mount -t ext4 /dev/sda /A are ambigous for userspace. Either a new
superblock has been created and mounted or an existing superblock has
been reused and a bind-mount has been created.

This becomes clear in the following example where two processes create
the same mount for the same block device:

P1 P2
fd_fs = fsopen("ext4"); fd_fs = fsopen("ext4");
fsconfig(fd_fs, FSCONFIG_SET_STRING, "source", "/dev/sda"); fsconfig(fd_fs, FSCONFIG_SET_STRING, "source", "/dev/sda");
fsconfig(fd_fs, FSCONFIG_SET_STRING, "dax", "always"); fsconfig(fd_fs, FSCONFIG_SET_STRING, "resuid", "1000");

// wins and creates superblock
fsconfig(fd_fs, FSCONFIG_CMD_CREATE, ...)
// finds compatible superblock of P1
// spins until P1 sets SB_BORN and grabs a reference
fsconfig(fd_fs, FSCONFIG_CMD_CREATE, ...)

fd_mnt1 = fsmount(fd_fs); fd_mnt2 = fsmount(fd_fs);
move_mount(fd_mnt1, "/A") move_mount(fd_mnt2, "/B")

Not just does P2 get a bind-mount but the mount options that P2
requestes are silently ignored. The VFS itself doesn't, can't and
shouldn't enforce filesystem specific mount option compatibility. It
only enforces incompatibility for read-only <-> read-write transitions:

mount -t ext4 /dev/sda /A
mount -t ext4 -o ro /dev/sda /B

The read-only request will fail with EBUSY as the VFS can't just
silently transition a superblock from read-write to read-only or vica
versa without risking security issues.

To userspace this silent superblock reuse can become a security issue in
because there is currently no straightforward way for userspace to know
that they did indeed manage to create a new superblock and didn't just
reuse an existing one.

This adds a new FSCONFIG_CMD_CREATE_EXCL command to fsconfig() that
returns EBUSY if an existing superblock would be reused. Userspace that
needs to be sure that it did create a new superblock with the requested
mount options can request superblock creation using this command. If the
command succeeds they can be sure that they did create a new superblock
with the requested mount options.

This requires the new mount api. With the old mount api it would be
necessary to plumb this through every legacy filesystem's
file_system_type->mount() method. If they want this feature they are
most welcome to switch to the new mount api.

Following is an analysis of the effect of FSCONFIG_CMD_CREATE_EXCL on
each high-level superblock creation helper:

(1) get_tree_nodev()

Always allocate new superblock. Hence, FSCONFIG_CMD_CREATE and
FSCONFIG_CMD_CREATE_EXCL are equivalent.

The binderfs or overlayfs filesystems are examples.

(4) get_tree_keyed()

Finds an existing superblock based on sb->s_fs_info. Hence,
FSCONFIG_CMD_CREATE would reuse an existing superblock whereas
FSCONFIG_CMD_CREATE_EXCL would reject it with EBUSY.

The mqueue or nfsd filesystems are examples.

(2) get_tree_bdev()

This effectively works like get_tree_keyed().

The ext4 or xfs filesystems are examples.

(3) get_tree_single()

Only one superblock of this filesystem type can ever exist.
Hence, FSCONFIG_CMD_CREATE would reuse an existing superblock
whereas FSCONFIG_CMD_CREATE_EXCL would reject it with EBUSY.

The securityfs or configfs filesystems are examples.

Note that some single-instance filesystems never destroy the
superblock once it has been created during the first mount. For
example, if securityfs has been mounted at least onces then the
created superblock will never be destroyed again as long as there is
still an LSM making use it. Consequently, even if securityfs is
unmounted and the superblock seemingly destroyed it really isn't
which means that FSCONFIG_CMD_CREATE_EXCL will continue rejecting
reusing an existing superblock.

This is acceptable thugh since special purpose filesystems such as
this shouldn't have a need to use FSCONFIG_CMD_CREATE_EXCL anyway
and if they do it's probably to make sure that mount options aren't
ignored.

Following is an analysis of the effect of FSCONFIG_CMD_CREATE_EXCL on
filesystems that make use of the low-level sget_fc() helper directly.
They're all effectively variants on get_tree_keyed(), get_tree_bdev(),
or get_tree_nodev():

(5) mtd_get_sb()

Similar logic to get_tree_keyed().

(6) afs_get_tree()

Similar logic to get_tree_keyed().

(7) ceph_get_tree()

Similar logic to get_tree_keyed().

Already explicitly allows forcing the allocation of a new superblock
via CEPH_OPT_NOSHARE. This turns it into get_tree_nodev().

(8) fuse_get_tree_submount()

Similar logic to get_tree_nodev().

(9) fuse_get_tree()

Forces reuse of existing FUSE superblock.

Forces reuse of existing superblock if passed in file refers to an
existing FUSE connection.
If FSCONFIG_CMD_CREATE_EXCL is specified together with an fd
referring to an existing FUSE connections this would cause the
superblock reusal to fail. If reusing is the intent then
FSCONFIG_CMD_CREATE_EXCL shouldn't be specified.

(10) fuse_get_tree()
-> get_tree_nodev()

Same logic as in get_tree_nodev().

(11) fuse_get_tree()
-> get_tree_bdev()

Same logic as in get_tree_bdev().

(12) virtio_fs_get_tree()

Same logic as get_tree_keyed().

(13) gfs2_meta_get_tree()

Forces reuse of existing gfs2 superblock.

Mounting gfs2meta enforces that a gf2s superblock must already
exist. If not, it will error out. Consequently, mounting gfs2meta
with FSCONFIG_CMD_CREATE_EXCL would always fail. If reusing is the
intent then FSCONFIG_CMD_CREATE_EXCL shouldn't be specified.

(14) kernfs_get_tree()

Similar logic to get_tree_keyed().

(15) nfs_get_tree_common()

Similar logic to get_tree_keyed().

Already explicitly allows forcing the allocation of a new superblock
via NFS_MOUNT_UNSHARED. This effectively turns it into
get_tree_nodev().

Link: [1] https://lore.kernel.org/linux-block/20230704-fasching-wertarbeit-7c6ffb01c83d@brauner
Link: [2] https://lore.kernel.org/linux-block/20230705-pumpwerk-vielversprechend-a4b1fd947b65@brauner
Link: [3] https://lore.kernel.org/linux-fsdevel/20230725-einnahmen-warnschilder-17779aec0a97@brauner
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230802-vfs-super-exclusive-v2-4-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...

super: remove get_tree_single_reconf()

The get_tree_single_reconf() helper isn't used anywhere. Remove it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Christoph Hellwig <hch@lst.de

super: remove get_tree_single_reconf()

The get_tree_single_reconf() helper isn't used anywhere. Remove it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230802-vfs-super-exclusive-v2-1-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...

fs: export setup_bdev_super

We'll want to use setup_bdev_super instead of duplicating it in nilfs2.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>

fs: export setup_bdev_super

We'll want to use setup_bdev_super instead of duplicating it in nilfs2.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Message-Id: <20230802154131.2221419-2-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...

fs_context: drop the unused lsm_flags member

This isn't ever used by VFS now, and it couldn't even work. Any FS that
uses the SECURITY_LSM_NATIVE_LABELS flag needs to also process the
value returned

fs_context: drop the unused lsm_flags member

This isn't ever used by VFS now, and it couldn't even work. Any FS that
uses the SECURITY_LSM_NATIVE_LABELS flag needs to also process the
value returned back from the LSM, so it needs to do its
security_sb_set_mnt_opts() call on its own anyway.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

show more ...

fs: simplify vfs_get_super

Remove the pointless keying argument and associated enum and pass the
fill_super callback and a "bool reconf" instead. Also mark the function
static given that there are

fs: simplify vfs_get_super

Remove the pointless keying argument and associated enum and pass the
fill_super callback and a "bool reconf" instead. Also mark the function
static given that there are no users outside of super.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

show more ...

fs: edit a comment made in bad taste

I know nobody likes a buzzkill, but I figure it's best to keep the
bad jokes appropriate for small children.

Signed-off-by: Paul Moore <paul@paul-moore.com>

devtmpfs regression fix: reconfigure on each mount

Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as "remount" options, so it updates the configuration of
the

devtmpfs regression fix: reconfigure on each mount

Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as "remount" options, so it updates the configuration of
the single super_block on each mount.

Since that was changed, the mount options used for devtmpfs are ignored.
This is a regression which affect systemd - which mounts devtmpfs with
"-o mode=755,size=4m,nr_inodes=1m".

This patch restores the "remount" effect by calling reconfigure_single()

Fixes: d401727ea0d7 ("devtmpfs: don't mix {ramfs,shmem}_fill_super() with mount_single()")
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

devtmpfs regression fix: reconfigure on each mount

commit a6097180d884ddab769fb25588ea8598589c218c upstream.

Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as

devtmpfs regression fix: reconfigure on each mount

commit a6097180d884ddab769fb25588ea8598589c218c upstream.

Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as "remount" options, so it updates the configuration of
the single super_block on each mount.

Since that was changed, the mount options used for devtmpfs are ignored.
This is a regression which affect systemd - which mounts devtmpfs with
"-o mode=755,size=4m,nr_inodes=1m".

This patch restores the "remount" effect by calling reconfigure_single()

Fixes: d401727ea0d7 ("devtmpfs: don't mix {ramfs,shmem}_fill_super() with mount_single()")
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests. Things like:

BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
RIP: 0010:kernfs_sop_show_path+0x1b/0x60

...or these others:

RIP: 0010:do_mkdirat+0x6a/0xf0
RIP: 0010:d_alloc_parallel+0x98/0x510
RIP: 0010:do_readlinkat+0x86/0x120

There were other less common instances of some kind of a general scribble
but the common theme was mount and cgroup and a dubious dentry triggering
the NULL dereference. I was only able to reproduce it under qemu by
replicating Richard's setup as closely as possible - I never did get it
to happen on bare metal, even while keeping everything else the same.

In commit 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
we see this as a part of the overall change:

--------------
struct cgroup_subsys *ss;
- struct dentry *dentry;

[...]

- dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root,
- CGROUP_SUPER_MAGIC, ns);

[...]

- if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
- struct super_block *sb = dentry->d_sb;
- dput(dentry);
+ ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
+ if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
+ struct super_block *sb = fc->root->d_sb;
+ dput(fc->root);
deactivate_locked_super(sb);
msleep(10);
return restart_syscall();
}
--------------

In changing from the local "*dentry" variable to using fc->root, we now
export/leave that dentry pointer in the file context after doing the dput()
in the unlikely "is_dying" case. With LTP doing a crazy amount of back to
back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely
becomes slightly likely and then bad things happen.

A fix would be to not leave the stale reference in fc->root as follows:

--------------
                dput(fc->root);
+ fc->root = NULL;
                deactivate_locked_super(sb);
--------------

...but then we are just open-coding a duplicate of fc_drop_locked() so we
simply use that instead.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: stable@vger.kernel.org # v5.1+
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Fixes: 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

show more ...

fs: add vfs_parse_fs_param_source() helper

Add a simple helper that filesystems can use in their parameter parser
to parse the "source" parameter. A few places open-coded this function
and that alre

fs: add vfs_parse_fs_param_source() helper

Add a simple helper that filesystems can use in their parameter parser
to parse the "source" parameter. A few places open-coded this function
and that already caused a bug in the cgroup v1 parser that we fixed.
Let's make it harder to get this wrong by introducing a helper which
performs all necessary checks.

Link: https://syzkaller.appspot.com/bug?id=6312526aba5beae046fdae8f00399f87aab48b12
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

commit 1e7107c5ef44431bc1ebbd4c353f1d7c22e5f2ec upstream.

Richard reported sporadic (roughly one in 10 or so) null dereferences a

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

commit 1e7107c5ef44431bc1ebbd4c353f1d7c22e5f2ec upstream.

Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests. Things like:

BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
RIP: 0010:kernfs_sop_show_path+0x1b/0x60

...or these others:

RIP: 0010:do_mkdirat+0x6a/0xf0
RIP: 0010:d_alloc_parallel+0x98/0x510
RIP: 0010:do_readlinkat+0x86/0x120

There were other less common instances of some kind of a general scribble
but the common theme was mount and cgroup and a dubious dentry triggering
the NULL dereference. I was only able to reproduce it under qemu by
replicating Richard's setup as closely as possible - I never did get it
to happen on bare metal, even while keeping everything else the same.

In commit 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
we see this as a part of the overall change:

--------------
struct cgroup_subsys *ss;
- struct dentry *dentry;

[...]

- dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root,
- CGROUP_SUPER_MAGIC, ns);

[...]

- if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
- struct super_block *sb = dentry->d_sb;
- dput(dentry);
+ ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
+ if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
+ struct super_block *sb = fc->root->d_sb;
+ dput(fc->root);
deactivate_locked_super(sb);
msleep(10);
return restart_syscall();
}
--------------

In changing from the local "*dentry" variable to using fc->root, we now
export/leave that dentry pointer in the file context after doing the dput()
in the unlikely "is_dying" case. With LTP doing a crazy amount of back to
back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely
becomes slightly likely and then bad things happen.

A fix would be to not leave the stale reference in fc->root as follows:

--------------
                dput(fc->root);
+ fc->root = NULL;
                deactivate_locked_super(sb);
--------------

...but then we are just open-coding a duplicate of fc_drop_locked() so we
simply use that instead.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: stable@vger.kernel.org # v5.1+
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Fixes: 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

fuse: reject options on reconfigure via fsconfig(2)

Previous patch changed handling of remount/reconfigure to ignore all
options, including those that are unknown to the fuse kernel fs. This was
do

fuse: reject options on reconfigure via fsconfig(2)

Previous patch changed handling of remount/reconfigure to ignore all
options, including those that are unknown to the fuse kernel fs. This was
done for backward compatibility, but this likely only affects the old
mount(2) API.

The new fsconfig(2) based reconfiguration could possibly be improved. This
would make the new API less of a drop in replacement for the old, OTOH this
is a good chance to get rid of some weirdnesses in the old API.

Several other behaviors might make sense:

1) unknown options are rejected, known options are ignored

2) unknown options are rejected, known options are rejected if the value
is changed, allowed otherwise

3) all options are rejected

Prior to the backward compatibility fix to ignore all options all known
options were accepted (1), even if they change the value of a mount
parameter; fuse_reconfigure() does not look at the config values set by
fuse_parse_param().

To fix that we'd need to verify that the value provided is the same as set
in the initial configuration (2). The major drawback is that this is much
more complex than just rejecting all attempts at changing options (3);
i.e. all options signify initial configuration values and don't make sense
on reconfigure.

This patch opts for (3) with the rationale that no mount options are
reconfigurable in fuse.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

show more ...

docs: filesystems: convert mount_api.txt to ReST

- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table ma

docs: filesystems: convert mount_api.txt to ReST

- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table markups;
- Add lists markups;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/32332c1659a28c22561cb5e64162c959856066b4.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

show more ...

prefix-handling analogues of errorf() and friends

called errorfc/infofc/warnfc/invalfc

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

add prefix to fs_context->log

... turning it into struct p_log embedded into fs_context. Initialize
the prefix with fs_type->name, turning fs_parse() into a trivial
inline wrapper for __fs_parse().

add prefix to fs_context->log

... turning it into struct p_log embedded into fs_context. Initialize
the prefix with fs_type->name, turning fs_parse() into a trivial
inline wrapper for __fs_parse().

This makes fs_parameter_description->name completely unused.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

show more ...

new primitive: __fs_parse()

fs_parse() analogue taking p_log instead of fs_context.
fs_parse() turned into a wrapper, callers in ceph_common and rbd
switched to __fs_parse().

As the result, fs_pars

new primitive: __fs_parse()

fs_parse() analogue taking p_log instead of fs_context.
fs_parse() turned into a wrapper, callers in ceph_common and rbd
switched to __fs_parse().

As the result, fs_parse() never gets NULL fs_context and neither
do fs_context-based logging primitives

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

show more ...

struct p_log, variants of warnf() et.al. taking that one instead

primitives for prefixed logging

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

teach logfc() to handle prefices, give it saner calling conventions

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

get rid of fs_value_is_filename_empty

Its behaviour is identical to that of fs_value_is_filename.
It makes no sense, anyway - LOOKUP_EMPTY affects nothing
whatsoever once the pathname has been impor

get rid of fs_value_is_filename_empty

Its behaviour is identical to that of fs_value_is_filename.
It makes no sense, anyway - LOOKUP_EMPTY affects nothing
whatsoever once the pathname has been imported from userland.
And both fs_value_is_filename and fs_value_is_filename_empty
carry an already imported pathname.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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vfs: subtype handling moved to fuse

The unused vfs code can be removed. Don't pass empty subtype (same as if
->parse callback isn't called).

The bits that are left involve determining whether it's

vfs: subtype handling moved to fuse

The unused vfs code can be removed. Don't pass empty subtype (same as if
->parse callback isn't called).

The bits that are left involve determining whether it's permitted to split the
filesystem type string passed in to mount(2). Consequently, this means that we
cannot get rid of the FS_HAS_SUBTYPE flag unless we define that a type string
with a dot in it always indicates a subtype specification.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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vfs: Add a single-or-reconfig keying to vfs_get_super()

Add an additional keying mode to vfs_get_super() to indicate that only a
single superblock should exist in the system, and that, if it does, f

vfs: Add a single-or-reconfig keying to vfs_get_super()

Add an additional keying mode to vfs_get_super() to indicate that only a
single superblock should exist in the system, and that, if it does, further
mounts should invoke reconfiguration upon it.

This allows mount_single() to be replaced.

[Fix by Eric Biggers folded in]

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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vfs: Create fs_context-aware mount_bdev() replacement

Create a function, get_tree_bdev(), that is fs_context-aware and a
->get_tree() counterpart of mount_bdev().

It caches the block device pointer

vfs: Create fs_context-aware mount_bdev() replacement

Create a function, get_tree_bdev(), that is fs_context-aware and a
->get_tree() counterpart of mount_bdev().

It caches the block device pointer in the fs_context struct so that this
information can be passed into sget_fc()'s test and set functions.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: linux-block@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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new helper: get_tree_keyed()

For vfs_get_keyed_super users.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

convenience helper: get_tree_single()

counterpart of mount_single(); switch fusectl to it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>