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* vfs: Commit to never having exectuables on proc and sysfs.Eric W. Biederman2015-07-101-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Today proc and sysfs do not contain any executable files. Several applications today mount proc or sysfs without noexec and nosuid and then depend on there being no exectuables files on proc or sysfs. Having any executable files show on proc or sysfs would cause a user space visible regression, and most likely security problems. Therefore commit to never allowing executables on proc and sysfs by adding a new flag to mark them as filesystems without executables and enforce that flag. Test the flag where MNT_NOEXEC is tested today, so that the only user visible effect will be that exectuables will be treated as if the execute bit is cleared. The filesystems proc and sysfs do not currently incoporate any executable files so this does not result in any user visible effects. This makes it unnecessary to vet changes to proc and sysfs tightly for adding exectuable files or changes to chattr that would modify existing files, as no matter what the individual file say they will not be treated as exectuable files by the vfs. Not having to vet changes to closely is important as without this we are only one proc_create call (or another goof up in the implementation of notify_change) from having problematic executables on proc. Those mistakes are all too easy to make and would create a situation where there are security issues or the assumptions of some program having to be broken (and cause userspace regressions). Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2015-07-032-4/+35
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull user namespace updates from Eric Biederman: "Long ago and far away when user namespaces where young it was realized that allowing fresh mounts of proc and sysfs with only user namespace permissions could violate the basic rule that only root gets to decide if proc or sysfs should be mounted at all. Some hacks were put in place to reduce the worst of the damage could be done, and the common sense rule was adopted that fresh mounts of proc and sysfs should allow no more than bind mounts of proc and sysfs. Unfortunately that rule has not been fully enforced. There are two kinds of gaps in that enforcement. Only filesystems mounted on empty directories of proc and sysfs should be ignored but the test for empty directories was insufficient. So in my tree directories on proc, sysctl and sysfs that will always be empty are created specially. Every other technique is imperfect as an ordinary directory can have entries added even after a readdir returns and shows that the directory is empty. Special creation of directories for mount points makes the code in the kernel a smidge clearer about it's purpose. I asked container developers from the various container projects to help test this and no holes were found in the set of mount points on proc and sysfs that are created specially. This set of changes also starts enforcing the mount flags of fresh mounts of proc and sysfs are consistent with the existing mount of proc and sysfs. I expected this to be the boring part of the work but unfortunately unprivileged userspace winds up mounting fresh copies of proc and sysfs with noexec and nosuid clear when root set those flags on the previous mount of proc and sysfs. So for now only the atime, read-only and nodev attributes which userspace happens to keep consistent are enforced. Dealing with the noexec and nosuid attributes remains for another time. This set of changes also addresses an issue with how open file descriptors from /proc/<pid>/ns/* are displayed. Recently readlink of /proc/<pid>/fd has been triggering a WARN_ON that has not been meaningful since it was added (as all of the code in the kernel was converted) and is not now actively wrong. There is also a short list of issues that have not been fixed yet that I will mention briefly. It is possible to rename a directory from below to above a bind mount. At which point any directory pointers below the renamed directory can be walked up to the root directory of the filesystem. With user namespaces enabled a bind mount of the bind mount can be created allowing the user to pick a directory whose children they can rename to outside of the bind mount. This is challenging to fix and doubly so because all obvious solutions must touch code that is in the performance part of pathname resolution. As mentioned above there is also a question of how to ensure that developers by accident or with purpose do not introduce exectuable files on sysfs and proc and in doing so introduce security regressions in the current userspace that will not be immediately obvious and as such are likely to require breaking userspace in painful ways once they are recognized" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: vfs: Remove incorrect debugging WARN in prepend_path mnt: Update fs_fully_visible to test for permanently empty directories sysfs: Create mountpoints with sysfs_create_mount_point sysfs: Add support for permanently empty directories to serve as mount points. kernfs: Add support for always empty directories. proc: Allow creating permanently empty directories that serve as mount points sysctl: Allow creating permanently empty directories that serve as mountpoints. fs: Add helper functions for permanently empty directories. vfs: Ignore unlocked mounts in fs_fully_visible mnt: Modify fs_fully_visible to deal with locked ro nodev and atime mnt: Refactor the logic for mounting sysfs and proc in a user namespace
| * sysfs: Add support for permanently empty directories to serve as mount points.Eric W. Biederman2015-07-011-0/+34
| | | | | | | | | | | | | | | | | | | | | | | | Add two functions sysfs_create_mount_point and sysfs_remove_mount_point that hang a permanently empty directory off of a kobject or remove a permanently emptpy directory hanging from a kobject. Export these new functions so modular filesystems can use them. Cc: stable@vger.kernel.org Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * mnt: Refactor the logic for mounting sysfs and proc in a user namespaceEric W. Biederman2015-05-131-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fresh mounts of proc and sysfs are a very special case that works very much like a bind mount. Unfortunately the current structure can not preserve the MNT_LOCK... mount flags. Therefore refactor the logic into a form that can be modified to preserve those lock bits. Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount of the filesystem be fully visible in the current mount namespace, before the filesystem may be mounted. Move the logic for calling fs_fully_visible from proc and sysfs into fs/namespace.c where it has greater access to mount namespace state. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | fs: sysfs: don't pass count == 0 to bin file readersVladimir Zapolskiy2015-06-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If count == 0 bytes are requested by a reader, sysfs_kf_bin_read() deliberately returns 0 without passing a potentially harmful value to some externally defined underlying battr->read() function. However in case of (pos == size && count) the next clause always sets count to 0 and this value is handed over to battr->read(). The change intends to make obsolete (and remove later) a redundant sanity check in battr->read(), if it is present, or add more protection to struct bin_attribute users, who does not care about input arguments. Signed-off-by: Vladimir Zapolskiy <vz@mleia.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | sysfs: disambiguate between "error code" and "failure" in commentsAntonio Ospite2015-05-241-3/+3
|/ | | | | | | | | | | | | The sentence "Returns 0 on success or error" might be misinterpreted as "the function will always returns 0", make it less ambiguous. Also, use the word "failure" as the contrary of "success". Signed-off-by: Antonio Ospite <ao2@ao2.it> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: Only accept read/write permissions for file attributesVivien Didelot2015-03-251-0/+6
| | | | | | | | | | | | | | | | For sysfs file attributes, only read and write permissions make sense. Mask provided attribute permissions accordingly and send a warning to the console if invalid permission bits are set. This patch is originally from Guenter [1] and includes the fixup explained in the thread, that is printing permissions in octal format and limiting the scope of attributes to SYSFS_PREALLOC | 0664. [1] https://lkml.org/lkml/2015/1/19/599 Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: Use only return value from is_visible for the file modeGuenter Roeck2015-03-251-3/+2
| | | | | | | | | | | | | | | | | | | | Up to now, is_visible can only be used to either remove visibility of a file entirely or to add permissions, but not to reduce permissions. This makes it impossible, for example, to use DEVICE_ATTR_RW to define file attributes and reduce permissions to read-only. This behavior is undesirable and unnecessarily complicates code which needs to reduce permissions; instead of just returning the desired permissions, it has to ensure that the permissions in the attribute variable declaration only reflect the minimal permissions ever needed. Change semantics of is_visible to only use the permissions returned from it instead of oring the returned value with the hard-coded permissions. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'driver-core-3.20-rc1' of ↵Linus Torvalds2015-02-151-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core patches from Greg KH: "Really tiny set of patches for this kernel. Nothing major, all described in the shortlog and have been in linux-next for a while" * tag 'driver-core-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: sysfs: fix warning when creating a sysfs group without attributes firmware_loader: handle timeout via wait_for_completion_interruptible_timeout() firmware_loader: abort request if wait_for_completion is interrupted firmware: Correct function name in comment device: Change dev_<level> logging functions to return void device: Fix dev_dbg_once macro
| * sysfs: fix warning when creating a sysfs group without attributesJavi Merino2015-02-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | When attempting to create a gropu without attrs, the warning prints the name of the group. However, the check for name being a NULL pointer is wrong: it uses the pointer to the name when it's NULL. Fix it to use the name if present, otherwise just put an empty string. Cc: Bruno Prémont <bonbons@linux-vserver.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | kernfs: remove KERNFS_STATIC_NAMETejun Heo2015-02-131-1/+1
|/ | | | | | | | | | | | | | | | | When a new kernfs node is created, KERNFS_STATIC_NAME is used to avoid making a separate copy of its name. It's currently only used for sysfs attributes whose filenames are required to stay accessible and unchanged. There are rare exceptions where these names are allocated and formatted dynamically but for the vast majority of cases they're consts in the rodata section. Now that kernfs is converted to use kstrdup_const() and kfree_const(), there's little point in keeping KERNFS_STATIC_NAME around. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrzej Hajda <a.hajda@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sysfs/kernfs: make read requests on pre-alloc files use the buffer.NeilBrown2014-11-071-4/+28
| | | | | | | | | | | | | | | | | | | | | | | To match the previous patch which used the pre-alloc buffer for writes, this patch causes reads to use the same buffer. This is not strictly necessary as the current seq_read() will allocate on first read, so user-space can trigger the required pre-alloc. But consistency is valuable. The read function is somewhat simpler than seq_read() and, for example, does not support reading from an offset into the file: reads must be at the start of the file. As seq_read() does not use the prealloc buffer, ->seq_show is incompatible with ->prealloc and caused an EINVAL return from open(). sysfs code which calls into kernfs always chooses the correct function. As the buffer is shared with writes and other reads, the mutex is extended to cover the copy_to_user. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs/kernfs: allow attributes to request write buffer be pre-allocated.NeilBrown2014-11-071-7/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | md/raid allows metadata management to be performed in user-space. A various times, particularly on device failure, the metadata needs to be updated before further writes can be permitted. This means that the user-space program which updates metadata much not block on writeout, and so must not allocate memory. mlockall(MCL_CURRENT|MCL_FUTURE) and pre-allocation can avoid all memory allocation issues for user-memory, but that does not help kernel memory. Several kernel objects can be pre-allocated. e.g. files opened before any writes to the array are permitted. However some kernel allocation happens in places that cannot be pre-allocated. In particular, writes to sysfs files (to tell md that it can now allow writes to the array) allocate a buffer using GFP_KERNEL. This patch allows attributes to be marked as "PREALLOC". In that case the maximal buffer is allocated when the file is opened, and then used on each write instead of allocating a new buffer. As the same buffer is now shared for all writes on the same file description, the mutex is extended to cover full use of the buffer including the copy_from_user(). The new __ATTR_PREALLOC() 'or's a new flag in to the 'mode', which is inspected by sysfs_add_file_mode_ns() to determine if the file should be marked as requiring prealloc. Despite the comment, we *do* use ->seq_show together with ->prealloc in this patch. The next patch fixes that. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fs: sysfs: return EGBIG on write if offset is larger than file sizeVladimir Zapolskiy2014-11-071-1/+1
| | | | | | | | | | | | | | | | | | According to the user expectations common utilities like dd or sh redirection operator > should work correctly over binary files from sysfs. At the moment doing excessive write can not be completed: write(1, "\0\0\0\0\0\0\0\0", 8) = 4 write(1, "\0\0\0\0", 4) = 0 write(1, "\0\0\0\0", 4) = 0 write(1, "\0\0\0\0", 4) = 0 ... Fix the problem by returning EFBIG described in man 2 write. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: move the last knowledge of sysfs out from kernfsJianyu Zhan2014-05-271-1/+3
| | | | | | | | | | | There is still one residue of sysfs remaining: the sb_magic SYSFS_MAGIC. However this should be kernfs user specific, so this patch moves it out. Kerrnfs user should specify their magic number while mouting. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: fix attribute_group bin file path on removalRobert ABEL2014-05-271-5/+5
| | | | | | | | | | Cody Schafer already fixed binary file creation for attribute groups, see [1]. This patch makes the appropriate changes for binary file removal of attribute groups. [1]: http://lkml.org/lkml/2014/2/27/832 Signed-off-by: Robert ABEL <rabel@cit-ec.uni-bielefeld.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: make sure read buffer is zeroedTejun Heo2014-05-201-1/+2
| | | | | | | | | | | | | | | | | | | | | | 13c589d5b0ac ("sysfs: use seq_file when reading regular files") switched sysfs from custom read implementation to seq_file to enable later transition to kernfs. After the change, the buffer passed to ->show() is acquired through seq_get_buf(); unfortunately, this introduces a subtle behavior change. Before the commit, the buffer passed to ->show() was always zero as it was allocated using get_zeroed_page(). Because seq_file doesn't clear buffers on allocation and neither does seq_get_buf(), after the commit, depending on the behavior of ->show(), we may end up exposing uninitialized data to userland thus possibly altering userland visible behavior and leaking information. Fix it by explicitly clearing the buffer. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Ron <ron@debian.org> Fixes: 13c589d5b0ac ("sysfs: use seq_file when reading regular files") Cc: stable <stable@vger.kernel.org> # 3.13+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs, sysfs, cgroup: restrict extra perm check on open to sysfsTejun Heo2014-05-131-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernfs open method - kernfs_fop_open() - inherited extra permission checks from sysfs. While the vfs layer allows ignoring the read/write permissions checks if the issuer has CAP_DAC_OVERRIDE, sysfs explicitly denied open regardless of the cap if the file doesn't have any of the UGO perms of the requested access or doesn't implement the requested operation. It can be debated whether this was a good idea or not but the behavior is too subtle and dangerous to change at this point. After cgroup got converted to kernfs, this extra perm check also got applied to cgroup breaking libcgroup which opens write-only files with O_RDWR as root. This patch gates the extra open permission check with a new flag KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK and enables it for sysfs. For sysfs, nothing changes. For cgroup, root now can perform any operation regardless of the permissions as it was before kernfs conversion. Note that kernfs still fails unimplemented operations with -EINVAL. While at it, add comments explaining KERNFS_ROOT flags. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Andrey Wagin <avagin@gmail.com> Tested-by: Andrey Wagin <avagin@gmail.com> Cc: Li Zefan <lizefan@huawei.com> References: http://lkml.kernel.org/g/CANaxB-xUm3rJ-Cbp72q-rQJO5mZe1qK6qXsQM=vh0U8upJ44+A@mail.gmail.com Fixes: 2bd59d48ebfb ("cgroup: convert to kernfs") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo2014-04-161-92/+0
| | | | | | | | | All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman2014-03-251-0/+92
| | | | | | | | | | | | | | | | | {sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. As reported by Stephen, this patch breaks linux-next as a ppc patch suddenly (after 2 years) started using this old api call. So revert it for now, it will go away in 3.15-rc2 when we can change the PPC call to the new api. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tejun Heo <tj@kernel.org> Cc: Stewart Smith <stewart@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 3.14-rc5 into driver-core-nextGreg Kroah-Hartman2014-03-021-2/+3
|\ | | | | | | We want the fixes in here.
| * sysfs: fix namespace refcnt leakLi Zefan2014-02-251-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As mount() and kill_sb() is not a one-to-one match, we shoudn't get ns refcnt unconditionally in sysfs_mount(), and instead we should get the refcnt only when kernfs_mount() allocated a new superblock. v2: - Changed the name of the new argument, suggested by Tejun. - Made the argument optional, suggested by Tejun. v3: - Make the new argument as second-to-last arg, suggested by Tejun. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> --- fs/kernfs/mount.c | 8 +++++++- fs/sysfs/mount.c | 5 +++-- include/linux/kernfs.h | 9 +++++---- 3 files changed, 15 insertions(+), 7 deletions(-) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | sysfs: create bin_attributes under the requested groupCody P Schafer2014-02-151-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | bin_attributes created/updated in create_files() (such as those listed via (struct device).attribute_groups) were not placed under the specified group, and instead appeared in the base kobj directory. Fix this by making bin_attributes use creating code similar to normal attributes. A quick grep shows that no one is using bin_attrs in a named attribute group yet, so we can do this without breaking anything in usespace. Note that I do not add is_visible() support to bin_attributes, though that could be done as well. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | kernfs: add CONFIG_KERNFSTejun Heo2014-02-071-0/+1
| | | | | | | | | | | | | | | | | | | | | | As sysfs was kernfs's only user, kernfs has been piggybacking on CONFIG_SYSFS; however, kernfs is scheduled to grow a new user very soon. Introduce a separate config option CONFIG_KERNFS which is to be selected by kernfs users. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | kernfs: implement kernfs_get_parent(), kernfs_name/path() and friendsTejun Heo2014-02-071-31/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kernfs_node->parent and ->name are currently marked as "published" indicating that kernfs users may access them directly; however, those fields may get updated by kernfs_rename[_ns]() and unrestricted access may lead to erroneous values or oops. Protect ->parent and ->name updates with a irq-safe spinlock kernfs_rename_lock and implement the following accessors for these fields. * kernfs_name() - format the node's name into the specified buffer * kernfs_path() - format the node's path into the specified buffer * pr_cont_kernfs_name() - pr_cont a node's name (doesn't need buffer) * pr_cont_kernfs_path() - pr_cont a node's path (doesn't need buffer) * kernfs_get_parent() - pin and return a node's parent All can be called under any context. The recursive sysfs_pathname() in fs/sysfs/dir.c is replaced with kernfs_path() and sysfs_rename_dir_ns() is updated to use kernfs_get_parent() instead of dereferencing parent directly. v2: Dummy definition of kernfs_path() for !CONFIG_KERNFS was missing static inline making it cause a lot of build warnings. Add it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | kernfs: allow nodes to be created in the deactivated stateTejun Heo2014-02-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, kernfs_nodes are made visible to userland on creation, which makes it difficult for kernfs users to atomically succeed or fail creation of multiple nodes. In addition, if something fails after creating some nodes, the created nodes might already be in use and their active refs need to be drained for removal, which has the potential to introduce tricky reverse locking dependency on active_ref depending on how the error path is synchronized. This patch introduces per-root flag KERNFS_ROOT_CREATE_DEACTIVATED. If set, all nodes under the root are created in the deactivated state and stay invisible to userland until explicitly enabled by the new kernfs_activate() API. Also, nodes which have never been activated are guaranteed to bypass draining on removal thus allowing error paths to not worry about lockding dependency on active_ref draining. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo2014-02-071-92/+0
| | | | | | | | | | | | | | | | | | All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo2014-02-071-0/+23
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref the task is holding, removes the self node, and restores active ref to the dead node so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. Note that manipulation of active ref is implemented in separate public functions - kernfs_[un]break_active_protection(). kernfs_remove_self() is the only user at the moment but this will be used to cater to more complex cases. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: kernfs_[un]break_active_protection() separated out from kernfs_remove_self() and exposed as public API. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its ↵Greg Kroah-Hartman2014-01-131-23/+0
| | | | | | | | | | | | | | | | | | | wrappers" This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman2014-01-131-0/+92
| | | | | | | | | | | | | | | | | {sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo2014-01-101-92/+0
| | | | | | | | | All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo2014-01-101-0/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref and deactivates using __kernfs_deactivate_self(), removes the self node, and restores active ref to the dead node using __kernfs_reactivate_self() so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: Updated to use __kernfs_{de|re}activate_self(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: add kernfs_dir_opsTejun Heo2013-12-171-1/+1
| | | | | | | | | | | | | | | | | | | | Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: mark static names with KERNFS_STATIC_NAMETejun Heo2013-12-171-2/+2
| | | | | | | | | | | | | | | | | | | | Because sysfs used struct attribute which are supposed to stay constant, sysfs didn't copy names when creating regular files. The specified string for name was supposed to stay constant. Such distinction isn't inherent for kernfs. kernfs_create_file[_ns]() should be able to take the same @name as kernfs_create_dir[_ns]() As there can be huge number of sysfs attributes, we still want to be able to use static names for sysfs attributes. This patch renames kernfs_create_file_ns_key() to __kernfs_create_file() and adds @name_is_static parameter so that the caller can explicitly indicate that @name can be used without copying. kernfs is updated to use KERNFS_STATIC_NAME to distinguish static and copied names. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: add @mode to kernfs_create_dir[_ns]()Tejun Heo2013-12-172-2/+4
| | | | | | | | | | | | | | sysfs assumed 0755 for all newly created directories and kernfs inherited it. This assumption is unnecessarily restrictive and inconsistent with kernfs_create_file[_ns](). This patch adds @mode parameter to kernfs_create_dir[_ns]() and update uses in sysfs accordingly. Among others, this will be useful for implementations of the planned ->mkdir() method. This patch doesn't introduce any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: s/sysfs/kernfs/ in constantsTejun Heo2013-12-113-3/+3
| | | | | | | | | | | | | | | | | | | | | | kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/SYSFS_DIR/KERNFS_DIR/ * s/SYSFS_KOBJ_ATTR/KERNFS_FILE/ * s/SYSFS_KOBJ_LINK/KERNFS_LINK/ * s/SYSFS_{TYPE_FLAGS}/KERNFS_{TYPE_FLAGS}/ * s/SYSFS_FLAG_{FLAG}/KERNFS_{FLAG}/ * s/sysfs_type()/kernfs_type()/ * s/SD_DEACTIVATED_BIAS/KN_DEACTIVATED_BIAS/ This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: s/sysfs/kernfs/ in various data structuresTejun Heo2013-12-111-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/sysfs_open_dirent/kernfs_open_node/ * s/sysfs_open_file/kernfs_open_file/ * s/sysfs_inode_attrs/kernfs_iattrs/ * s/sysfs_addrm_cxt/kernfs_addrm_cxt/ * s/sysfs_super_info/kernfs_super_info/ * s/sysfs_info()/kernfs_info()/ * s/sysfs_open_dirent_lock/kernfs_open_node_lock/ * s/sysfs_open_file_mutex/kernfs_open_file_mutex/ * s/sysfs_of()/kernfs_of()/ This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: drop s_ prefix from kernfs_node membersTejun Heo2013-12-113-17/+17
| | | | | | | | | | | | | | | | | kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. s_ prefix for kernfs members is used inconsistently and a misnomer now. It's not like kernfs_node is used widely across the kernel making the ability to grep for the members particularly useful. Let's just drop the prefix. This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordinglyTejun Heo2013-12-116-185/+185
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/sysfs_elem_dir/kernfs_elem_dir/ * s/sysfs_elem_symlink/kernfs_elem_symlink/ * s/sysfs_elem_attr/kernfs_elem_file/ * s/sysfs_dirent/kernfs_node/ * s/sd/kn/ in kernfs proper * s/parent_sd/parent/ * s/target_sd/target/ * s/dir_sd/parent/ * s/to_sysfs_dirent()/rb_to_kn()/ * misc renames of local vars when they conflict with the above Because md, mic and gpio dig into sysfs details, this patch ends up modifying them. All are sysfs_dirent renames and trivial. While we can avoid these by introducing a dummy wrapping struct sysfs_dirent around kernfs_node, given the limited usage outside kernfs and sysfs proper, I don't think such workaround is called for. This patch is strictly rename only and doesn't introduce any functional difference. - mic / gpio renames were missing. Spotted by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Neil Brown <neilb@suse.de> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: fix use-after-free in sysfs_kill_sb()Tejun Heo2013-12-101-1/+3
| | | | | | | | | | | | | | | While restructuring the [u]mount path, 4b93dc9b1c68 ("sysfs, kernfs: prepare mount path for kernfs") incorrectly updated sysfs_kill_sb() so that it first kills super_block and then tries to dereference its namespace tag to drop it. Fix it by caching namespace tag before killing the superblock and then drop the cached namespace tag. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Tested-by: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/g/20131205031051.GC5135@yliu-dev.sh.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs: bail early from kernfs_file_mmap() to avoid spurious lockdep warningTejun Heo2013-12-101-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is v3.14 fix for the same issue that a8b14744429f ("sysfs: give different locking key to regular and bin files") addresses for v3.13. Due to the extensive kernfs reorganization in v3.14 branch, the same fix couldn't be ported as-is. The v3.13 fix was ignored while merging it into v3.14 branch. 027a485d12e0 ("sysfs: use a separate locking class for open files depending on mmap") assigned different lockdep key to sysfs_open_file->mutex depending on whether the file implements mmap or not in an attempt to avoid spurious lockdep warning caused by merging of regular and bin file paths. While this restored some of the original behavior of using different locks (at least lockdep is concerned) for the different clases of files. The restoration wasn't full because now the lockdep key assignment depends on whether the file has mmap or not instead of whether it's a regular file or not. This means that bin files which don't implement mmap will get assigned the same lockdep class as regular files. This is problematic because file_operations for bin files still implements the mmap file operation and checking whether the sysfs file actually implements mmap happens in the file operation after grabbing @sysfs_open_file->mutex. We still end up adding locking dependency from mmap locking to sysfs_open_file->mutex to the regular file mutex which triggers spurious circular locking warning. For v3.13, a8b14744429f ("sysfs: give different locking key to regular and bin files") fixed it by giving sysfs_open_file->mutex different lockdep keys depending on whether the file is regular or bin instead of whether mmap exists or not; however, due to the way sysfs is now layered behind kernfs, this approach is no longer viable. kernfs can tell whether a sysfs node has mmap implemented or not but can't tell whether a bin file from a regular one. This patch updates kernfs such that kernfs_file_mmap() checks SYSFS_FLAG_HAS_MMAP and bail before grabbing sysfs_open_file->mutex so that it doesn't add spurious locking dependency from mmap to sysfs_open_file->mutex and changes sysfs so that it specifies kernfs_ops->mmap iff the sysfs file implements mmap. Combined, this ensures that sysfs_open_file->mutex is grabbed under mmap path iff the sysfs file actually implements mmap. As sysfs_open_file->mutex is already given a different lockdep key if mmap is implemented, this removes the spurious locking dependency. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: remove cross inclusions of internal headersTejun Heo2013-11-291-1/+0
| | | | | | | | | | | | | | fs/kernfs/kernfs-internal.h needed to include fs/sysfs/sysfs.h because part of kernfs core implementation was living in sysfs. fs/sysfs/sysfs.h needed to include fs/kernfs/kernfs-internal.h because include/linux/kernfs.h didn't expose enough interface. The separation is complete and neither is true anymore. Remove the cross inclusion and make sysfs a proper user of kernfs. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: implement kernfs_ns_enabled()Tejun Heo2013-11-291-1/+1
| | | | | | | | | | | | | | | fs/sysfs/symlink.c::sysfs_delete_link() tests @sd->s_flags for SYSFS_FLAG_NS. Let's add kernfs_ns_enabled() so that sysfs doesn't have to test sysfs_dirent flag directly. This makes things tidier for kernfs proper too. This is purely cosmetic. v2: To avoid possible NULL deref, use noop dummy implementation which always returns false when !CONFIG_SYSFS. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: move mount core code to fs/kernfs/mount.cTejun Heo2013-11-292-170/+0
| | | | | | | | | | | Move core mount code to fs/kernfs/mount.c. The respective declarations in fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h. This is pure relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: prepare mount path for kernfsTejun Heo2013-11-291-32/+72
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges mount path so that the kernfs and sysfs parts are separate. * As sysfs_super_info won't be visible outside kernfs proper, kernfs_super_ns() is added to allow kernfs users to access a super_block's namespace tag. * Generic mount operation is separated out into kernfs_mount_ns(). sysfs_mount() now just performs sysfs-specific permission check, acquires namespace tag, and invokes kernfs_mount_ns(). * Generic superblock release is separated out into kernfs_kill_sb() which can be used directly as file_system_type->kill_sb(). As sysfs needs to put the namespace tag, sysfs_kill_sb() wraps kernfs_kill_sb() with ns tag put. * sysfs_dir_cachep init and sysfs_inode_init() are separated out into kernfs_init(). kernfs_init() uses only small amount of memory and trying to handle and propagate kernfs_init() failure doesn't make much sense. Use SLAB_PANIC for sysfs_dir_cachep and make sysfs_inode_init() panic on failure. After this change, kernfs_init() should be called before sysfs_init(), fs/namespace.c::mnt_init() modified accordingly. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: make super_blocks bind to different kernfs_rootsTejun Heo2013-11-292-4/+12
| | | | | | | | | | | | | | | kernfs is being updated to allow multiple sysfs_dirent hierarchies so that it can also be used by other users. Currently, sysfs super_blocks are always attached to one kernfs_root - sysfs_root - and distinguished only by their namespace tags. This patch adds sysfs_super_info->root and update sysfs_fill/test_super() so that super_blocks are identified by the combination of both the associated kernfs_root and namespace tag. This allows mounting different kernfs hierarchies. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: implement kernfs_create/destroy_root()Tejun Heo2013-11-291-11/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There currently is single kernfs hierarchy in the whole system which is used for sysfs. kernfs needs to support multiple hierarchies to allow other users. This patch introduces struct kernfs_root which serves as the root of each kernfs hierarchy and implements kernfs_create/destroy_root(). * Each kernfs_root is associated with a root sd (sysfs_dentry). The root is freed when the root sd is released and kernfs_destory_root() simply invokes kernfs_remove() on the root sd. sysfs_remove_one() is updated to handle release of the root sd. Note that ps_iattr update in sysfs_remove_one() is trivially updated for readability. * Root sd's are now dynamically allocated using sysfs_new_dirent(). Update sysfs_alloc_ino() so that it gives out ino from 1 so that the root sd still gets ino 1. * While kernfs currently only points to the root sd, it'll soon grow fields which are specific to each hierarchy. As determining a given sd's root will be necessary, sd->s_dir.root is added. This backlink fits better as a separate field in sd; however, sd->s_dir is inside union with space to spare, so use it to save space and provide kernfs_root() accessor to determine the root sd. * As hierarchies may be destroyed now, each mount needs to hold onto the hierarchy it's attached to. Update sysfs_fill_super() and sysfs_kill_sb() so that they get and put the kernfs_root respectively. * sysfs_root is replaced with kernfs_root which is dynamically created by invoking kernfs_create_root() from sysfs_init(). This patch doesn't introduce any visible behavior changes. v2: kernfs_create_root() forgot to set @sd->priv. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: introduce sysfs_root_sdTejun Heo2013-11-294-9/+11
| | | | | | | | | | | | | Currently, it's assumed that there's a single kernfs hierarchy in the system anchored at sysfs_root which is defined as a global struct. To allow other users of kernfs, this will be made dynamic. Introduce a new global variable sysfs_root_sd which points to &sysfs_root and convert all &sysfs_root users. This patch doesn't introduce any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: no need to kern_mount() sysfs from sysfs_init()Tejun Heo2013-11-291-16/+7
| | | | | | | | | | | | | It has been very long since sysfs depended on vfs to keep track of internal states and whether sysfs is mounted or not doesn't make any difference to sysfs's internal operation. In addition to init and filesystem type registration, sysfs_init() invokes kern_mount() to create in-kernel mount of sysfs. This internal mounting doesn't server any purpose anymore. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sysfs, kernfs: make sysfs_super_info->ns constTejun Heo2013-11-292-8/+8
| | | | | | | | | | Add const qualifier to sysfs_super_info->ns so that it's consistent with other namespace tag usages in sysfs. Because kobject doesn't use const qualifier for namespace tags, this ends up requiring an explicit cast to drop const qualifier in free_sysfs_super_info(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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