Prior to this change 'on->nr_mmapped' tracked the total number of
mmaps across all of its associated open files via kernfs_fop_mmap().
Thus if the file descriptor associated with a kernfs_open_file was
mmapped 10 times then we would have: 'of->mmapped = true' and
'of_on(of)->nr_mmapped = 10'.
The problem is that closing or draining a 'of->mmapped' file would
only decrement one from the 'of_on(of)->nr_mmapped' counter.
For e.g. we have this from kernfs_unlink_open_file():
if (of->mmapped)
on->nr_mmapped--;
The WARN_ON_ONCE(on->nr_mmapped) in kernfs_drain_open_files() is
easy to reproduce by:
1. opening a (mmap-able) kernfs file.
2. mmap-ing that file more than once (mapping just once masks the issue).
3. trigger a drain of that kernfs file.
Modulo out-of-tree patches I was able to trigger this reliably by
identifying pci device nodes in sysfs that have resource regions
that are mmap-able and that don't have any driver attached to them
(steps 1 and 2). For step 3 we can "echo 1 > remove" to trigger a
kernfs_drain.
Signed-off-by: Neel Natu <neelnatu@google.com>
Link: https://lore.kernel.org/r/20240127234636.609265-1-neelnatu@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is the set of driver core updates for 6.7-rc1. Nothing major in
here at all, just a small number of changes including:
- minor cleanups and updates from Andy Shevchenko
- __counted_by addition
- firmware_loader update for aborting loads cleaner
- other minor changes, details in the shortlog
- documentation update
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the set of driver core updates for 6.7-rc1. Nothing major in
here at all, just a small number of changes including:
- minor cleanups and updates from Andy Shevchenko
- __counted_by addition
- firmware_loader update for aborting loads cleaner
- other minor changes, details in the shortlog
- documentation update
All of these have been in linux-next for a while with no reported
issues"
* tag 'driver-core-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (21 commits)
firmware_loader: Abort all upcoming firmware load request once reboot triggered
firmware_loader: Refactor kill_pending_fw_fallback_reqs()
Documentation: security-bugs.rst: linux-distros relaxed their rules
driver core: Release all resources during unbind before updating device links
driver core: class: remove boilerplate code
driver core: platform: Annotate struct irq_affinity_devres with __counted_by
resource: Constify resource crosscheck APIs
resource: Unify next_resource() and next_resource_skip_children()
resource: Reuse for_each_resource() macro
PCI: Implement custom llseek for sysfs resource entries
kernfs: sysfs: support custom llseek method for sysfs entries
debugfs: Fix __rcu type comparison warning
device property: Replace custom implementation of COUNT_ARGS()
drivers: base: test: Make property entry API test modular
driver core: Add missing parameter description to __fwnode_link_add()
device property: Clarify usage scope of some struct fwnode_handle members
devres: rename the first parameter of devm_add_action(_or_reset)
driver core: platform: Unify the firmware node type check
driver core: platform: Use temporary variable in platform_device_add()
driver core: platform: Refactor error path in a couple places
...
It seems strange that kernfs should be an outlier with a set_policy and
get_policy in its kernfs_vm_ops. Ah, it dates back to v2.6.30's commit
095160aee9 ("sysfs: fix some bin_vm_ops errors"), when I had crashed on
powerpc's pci_mmap_legacy_page_range() fallback to shmem_zero_setup().
Well, that was commendably thorough, to give sysfs-bin a set_policy and
get_policy, just to avoid the way it was coded resulting in EINVAL from
mmap when CONFIG_NUMA; but somehow feels a bit over-the-top to me now.
It's easier to say that nobody should expect to manage a shmem object's
shared NUMA mempolicy via some kernfs backdoor to that object: delete that
code (and there's no longer an EINVAL from mmap in the NUMA case).
This then leaves set_policy/get_policy as implemented only by shmem -
though importantly also by SysV SHM, which has to interface with shmem
which implements them, and with SHM_HUGETLB which does not.
Link: https://lkml.kernel.org/r/302164-a760-4a9e-879b-6870c9b4013@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun heo <tj@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
As of now, seeking in sysfs files is handled by generic_file_llseek().
There are situations where one may want to customize seeking logic:
- Many sysfs entries are fixed files while generic_file_llseek() accepts
past-the-end positions. Not only being useless by itself, this
also means a bug in userspace code will trigger not at lseek(), but at
some later point making debugging harder.
- generic_file_llseek() relies on f_mapping->host to get the file size
which might not be correct for all sysfs entries.
See commit 636b21b501 ("PCI: Revoke mappings like devmem") as an example.
Implement llseek method to override this behavior at sysfs attribute
level. The method is optional, and if it is absent,
generic_file_llseek() is called to preserve backwards compatibility.
Signed-off-by: Valentine Sinitsyn <valesini@yandex-team.ru>
Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use copy_splice_read() for tty, procfs, kernfs and random files rather
than going through generic_file_splice_read() as they just copy the file
into the output buffer and don't splice pages. This avoids the need for
them to have a ->read_folio() to satisfy filemap_splice_read().
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cc: Christoph Hellwig <hch@lst.de>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: Miklos Szeredi <miklos@szeredi.hu>
cc: Arnd Bergmann <arnd@arndb.de>
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20230522135018.2742245-13-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Right now per-fs kernfs_rwsem protects list of kernfs_super_info instances
for a kernfs_root. Since kernfs_rwsem is used to synchronize several other
operations across kernfs and since most of these operations don't impact
kernfs_super_info, we can use a separate per-fs rwsem to synchronize access
to list of kernfs_super_info.
This helps in reducing contention around kernfs_rwsem and also allows
operations that change/access list of kernfs_super_info to proceed without
contending for kernfs_rwsem.
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20230309110932.2889010-3-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix kernel-doc warnings. Many of these are about a function's
return value, so use the kernel-doc Return: format to fix those
Use % prefix on numeric constant values.
dir.c: fix typos/spellos
file.c fix typo: s/taret/target/
Fix all of these kernel-doc warnings:
dir.c:305: warning: missing initial short description on line:
* kernfs_name_hash
dir.c:137: warning: No description found for return value of 'kernfs_path_from_node_locked'
dir.c:196: warning: No description found for return value of 'kernfs_name'
dir.c:224: warning: No description found for return value of 'kernfs_path_from_node'
dir.c:292: warning: No description found for return value of 'kernfs_get_parent'
dir.c:312: warning: No description found for return value of 'kernfs_name_hash'
dir.c:404: warning: No description found for return value of 'kernfs_unlink_sibling'
dir.c:588: warning: No description found for return value of 'kernfs_node_from_dentry'
dir.c:806: warning: No description found for return value of 'kernfs_find_ns'
dir.c:879: warning: No description found for return value of 'kernfs_find_and_get_ns'
dir.c:904: warning: No description found for return value of 'kernfs_walk_and_get_ns'
dir.c:927: warning: No description found for return value of 'kernfs_create_root'
dir.c:996: warning: No description found for return value of 'kernfs_root_to_node'
dir.c:1016: warning: No description found for return value of 'kernfs_create_dir_ns'
dir.c:1048: warning: No description found for return value of 'kernfs_create_empty_dir'
dir.c:1306: warning: No description found for return value of 'kernfs_next_descendant_post'
dir.c:1568: warning: No description found for return value of 'kernfs_remove_self'
dir.c:1630: warning: No description found for return value of 'kernfs_remove_by_name_ns'
dir.c:1667: warning: No description found for return value of 'kernfs_rename_ns'
file.c:66: warning: No description found for return value of 'of_on'
file.c:88: warning: No description found for return value of 'kernfs_deref_open_node_locked'
file.c:1036: warning: No description found for return value of '__kernfs_create_file'
inode.c💯 warning: No description found for return value of 'kernfs_setattr'
mount.c:160: warning: No description found for return value of 'kernfs_root_from_sb'
mount.c:198: warning: No description found for return value of 'kernfs_node_dentry'
mount.c:302: warning: No description found for return value of 'kernfs_super_ns'
mount.c:318: warning: No description found for return value of 'kernfs_get_tree'
symlink.c:28: warning: No description found for return value of 'kernfs_create_link'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20221112031456.22980-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Track the number of mmapped files and files that need to be released and
skip kernfs_drain_open_file() if both are zero, which are the precise
conditions which require draining open_files. The early exit test is
factored into kernfs_should_drain_open_files() which is now tested by
kernfs_drain_open_files()'s caller - kernfs_drain().
This isn't a meaningful optimization on its own but will enable future
stand-alone kernfs_deactivate() implementation.
v2: Chengming noticed that on->nr_to_release was leaking after ->open()
failure. Fix it by telling kernfs_unlink_open_file() that it's called
from the ->open() fail path and should dec the counter. Use kzalloc() to
allocate kernfs_open_node so that the tracking fields are correctly
initialized.
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-5-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Factor out commont part. This is cleaner and should help with future
changes. No functional changes.
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-4-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs_node->attr.open is an RCU pointer to kernfs_open_node. However, RCU
dereference is currently only used in kernfs_notify(). Everywhere else,
either we're holding the lock which protects it or know that the
kernfs_open_node is pinned becaused we have a pointer to a kernfs_open_file
which is hanging off of it.
kernfs_deref_open_node() is used for the latter case - accessing
kernfs_open_node from kernfs_open_file. The lifetime and visibility rules
are simple and clear here. To someone who can access a kernfs_open_file, its
kernfs_open_node is pinned and visible through of->kn->attr.open.
Replace kernfs_deref_open_node() which simpler of_on(). The former takes
both @kn and @of and RCU deref @kn->attr.open while sanity checking with
@of. The latter takes @of and uses protected deref on of->kn->attr.open.
As the return value can't be NULL, remove the error handling in the callers
too.
This shouldn't cause any functional changes.
Cc: Imran Khan <imran.f.khan@oracle.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-2-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit b8f35fa118.
This is causing regression due to same kernfs_node getting
added multiple times in kernfs_notify_list so revert it until
safe way of using llist in this context is found.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Michael Walle <michael@walle.cc>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220705201026.2487665-1-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In current kernfs design a single mutex, kernfs_open_file_mutex, protects
the list of kernfs_open_file instances corresponding to a sysfs attribute.
So even if different tasks are opening or closing different sysfs files
they can contend on osq_lock of this mutex. The contention is more apparent
in large scale systems with few hundred CPUs where most of the CPUs have
running tasks that are opening, accessing or closing sysfs files at any
point of time.
Using hashed mutexes in place of a single global mutex, can significantly
reduce contention around global mutex and hence can provide better
scalability. Moreover as these hashed mutexes are not part of kernfs_node
objects we will not see any singnificant change in memory utilization of
kernfs based file systems like sysfs, cgroupfs etc.
Modify interface introduced in previous patch to make use of hashed
mutexes. Use kernfs_node address as hashing key.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220615021059.862643-5-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This allows to change underlying mutex locking, without needing to change
the users of the lock. For example next patch modifies this interface to
use hashed mutexes in place of a single global kernfs_open_file_mutex.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220615021059.862643-4-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
At present kernfs_notify_list is implemented as a singly linked
list of kernfs_node(s), where last element points to itself and
value of ->attr.next tells if node is present on the list or not.
Both addition and deletion to list happen under kernfs_notify_lock.
Change kernfs_notify_list to llist so that addition to list can heppen
locklessly.
Suggested by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220615021059.862643-3-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After removal of kernfs_open_node->refcnt in the previous patch,
kernfs_open_node_lock can be removed as well by making ->attr.open
RCU protected. kernfs_put_open_node can delegate freeing to ->attr.open
to RCU and other readers of ->attr.open can do so under rcu_read_(un)lock.
Suggested by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220615021059.862643-2-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since previous 'rc = -EINVAL;', rc value doesn't change, so not
necessary to re-assign it again.
Signed-off-by: Lin Feng <linf@wangsu.com>
Link: https://lore.kernel.org/r/20220617091746.206515-1-linf@wangsu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since we are no longer using refcnt for kernfs_open_node instances, rename
kernfs_put_open_node to kernfs_unlink_open_file to reflect this change.
Also update function description and inline comments accordingly.
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220504095123.295859-2-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The decision to free kernfs_open_node object in kernfs_put_open_node can
be taken based on whether kernfs_open_node->files list is empty or not. As
far as kernfs_drain_open_files is concerned it can't overlap with
kernfs_fops_open and hence can check for ->attr.open optimistically
(if ->attr.open is NULL) or under kernfs_open_file_mutex (if it needs to
traverse the ->files list.) Thus kernfs_drain_open_files can work w/o ref
counting involved kernfs_open_node as well.
So remove ->refcnt and modify the above mentioned users accordingly.
Suggested by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20220324103040.584491-2-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull vfs updates from Al Viro:
"Assorted bits and pieces"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
aio: drop needless assignment in aio_read()
clean overflow checks in count_mounts() a bit
seq_file: fix NULL pointer arithmetic warning
uml/x86: use x86 load_unaligned_zeropad()
asm/user.h: killed unused macros
constify struct path argument of finish_automount()/do_add_mount()
fs: Remove FIXME comment in generic_write_checks()
Implement conditional logic in order to replace NULL pointer arithmetic.
The use of NULL pointer arithmetic was pointed out by clang with the
following warning:
fs/kernfs/file.c:128:15: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
return NULL + !*ppos;
~~~~ ^
fs/seq_file.c:559:14: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
return NULL + (*pos == 0);
Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The kernfs implementation has big lock granularity(kernfs_rwsem) so
every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the
lock. It makes trouble for some cases to wait the global lock
for a long time even though they are totally independent contexts
each other.
A general example is process A goes under direct reclaim with holding
the lock when it accessed the file in sysfs and process B is waiting
the lock with exclusive mode and then process C is waiting the lock
until process B could finish the job after it gets the lock from
process A.
This patch switches the global kernfs_rwsem to per-fs lock, which
put the rwsem into kernfs_root.
Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/20211118230008.2679780-1-minchan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The kernfs global lock restricts the ability to perform kernfs node
lookup operations in parallel during path walks.
Change the kernfs mutex to an rwsem so that, when opportunity arises,
node searches can be done in parallel with path walk lookups.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642770946.63632.2218304587223241374.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Wire up the splice_read and splice_write methods to the default
helpers using ->read_iter and ->write_iter now that those are
implemented for kernfs. This restores support to use splice and
sendfile on kernfs files.
Fixes: 36e2c7421f ("fs: don't allow splice read/write without explicit ops")
Reported-by: Siddharth Gupta <sidgup@codeaurora.org>
Tested-by: Siddharth Gupta <sidgup@codeaurora.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210120204631.274206-4-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Switch kernfs to implement the write_iter method instead of plain old
write to prepare to supporting splice and sendfile again.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210120204631.274206-3-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Switch kernfs to implement the read_iter method instead of plain old
read to prepare to supporting splice and sendfile again.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210120204631.274206-2-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The arguments of fsnotify() are overloaded and mean different things
for different event types.
Replace the to_tell argument with separate arguments @dir and @inode,
because we may be sending to both dir and child. Using the @data
argument to pass the child is not enough, because dirent events pass
this argument (for audit), but we do not report to child.
Document the new fsnotify() function argumenets.
Link: https://lore.kernel.org/r/20200722125849.17418-7-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Instead of calling fsnotify() twice, once with parent inode and once
with child inode, if event should be sent to parent inode, send it
with both parent and child inodes marks in object type iterator and call
the backend handle_event() callback only once.
The parent inode is assigned to the standard "inode" iterator type and
the child inode is assigned to the special "child" iterator type.
In that case, the bit FS_EVENT_ON_CHILD will be set in the event mask,
the dir argument to handle_event will be the parent inode, the file_name
argument to handle_event is non NULL and refers to the name of the child
and the child inode can be accessed with fsnotify_data_inode().
This will allow fanotify to make decisions based on child or parent's
ignored mask. For example, when a parent is interested in a specific
event on its children, but a specific child wishes to ignore this event,
the event will not be reported. This is not what happens with current
code, but according to man page, it is the expected behavior.
Link: https://lore.kernel.org/r/20200716084230.30611-15-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
When creating an FS_MODIFY event on inode itself (not on parent)
the file_name argument should be NULL.
The change to send a non NULL name to inode itself was done on purpuse
as part of another commit, as Tejun writes: "...While at it, supply the
target file name to fsnotify() from kernfs_node->name.".
But this is wrong practice and inconsistent with inotify behavior when
watching a single file. When a child is being watched (as opposed to the
parent directory) the inotify event should contain the watch descriptor,
but not the file name.
Fixes: df6a58c5c5 ("kernfs: don't depend on d_find_any_alias()...")
Link: https://lore.kernel.org/r/20200708111156.24659-5-amir73il@gmail.com
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The kernfs_node lockdep tracking is being done on kn->active, the
active reference count. The other reference count (kn->count) is not
tracked by lockdep. So change the lockdep name to reflect what it is
tracking.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20200402171056.27871-1-longman@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs_node->id is currently a union kernfs_node_id which represents
either a 32bit (ino, gen) pair or u64 value. I can't see much value
in the usage of the union - all that's needed is a 64bit ID which the
current code is already limited to. Using a union makes the code
unnecessarily complicated and prevents using 64bit ino without adding
practical benefits.
This patch drops union kernfs_node_id and makes kernfs_node->id a u64.
ino is stored in the lower 32bits and gen upper. Accessors -
kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the
ino and gen. This simplifies ID handling less cumbersome and will
allow using 64bit inos on supported archs.
This patch doesn't make any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexei Starovoitov <ast@kernel.org>
Based on 1 normalized pattern(s):
this file is released under the gplv2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 68 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Note that in fnsotify_move() and fsnotify_link() we are guaranteed
that dentry->d_name won't change during the fsnotify() evaluation
(by having the parent directory locked exclusive), so we don't
need to fetch dentry->d_name.name in the callers. In fsnotify_dirent()
the same stability of dentry->d_name is also true, but it's a bit
more convoluted - there is one callchain (devpts_pty_new() ->
fsnotify_create() -> fsnotify_dirent()) where the parent is _not_
locked, but on devpts ->d_name of everything is unchanging; it
has neither explicit nor implicit renames.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Patch series "psi: pressure stall monitors", v3.
Android is adopting psi to detect and remedy memory pressure that
results in stuttering and decreased responsiveness on mobile devices.
Psi gives us the stall information, but because we're dealing with
latencies in the millisecond range, periodically reading the pressure
files to detect stalls in a timely fashion is not feasible. Psi also
doesn't aggregate its averages at a high enough frequency right now.
This patch series extends the psi interface such that users can
configure sensitive latency thresholds and use poll() and friends to be
notified when these are breached.
As high-frequency aggregation is costly, it implements an aggregation
method that is optimized for fast, short-interval averaging, and makes
the aggregation frequency adaptive, such that high-frequency updates
only happen while monitored stall events are actively occurring.
With these patches applied, Android can monitor for, and ward off,
mounting memory shortages before they cause problems for the user. For
example, using memory stall monitors in userspace low memory killer
daemon (lmkd) we can detect mounting pressure and kill less important
processes before device becomes visibly sluggish.
In our memory stress testing psi memory monitors produce roughly 10x
less false positives compared to vmpressure signals. Having ability to
specify multiple triggers for the same psi metric allows other parts of
Android framework to monitor memory state of the device and act
accordingly.
The new interface is straightforward. The user opens one of the
pressure files for writing and writes a trigger description into the
file descriptor that defines the stall state - some or full, and the
maximum stall time over a given window of time. E.g.:
/* Signal when stall time exceeds 100ms of a 1s window */
char trigger[] = "full 100000 1000000";
fd = open("/proc/pressure/memory");
write(fd, trigger, sizeof(trigger));
while (poll() >= 0) {
...
}
close(fd);
When the monitored stall state is entered, psi adapts its aggregation
frequency according to what the configured time window requires in order
to emit event signals in a timely fashion. Once the stalling subsides,
aggregation reverts back to normal.
The trigger is associated with the open file descriptor. To stop
monitoring, the user only needs to close the file descriptor and the
trigger is discarded.
Patches 1-4 prepare the psi code for polling support. Patch 5
implements the adaptive polling logic, the pressure growth detection
optimized for short intervals, and hooks up write() and poll() on the
pressure files.
The patches were developed in collaboration with Johannes Weiner.
This patch (of 5):
Kernfs has a standardized poll/notification mechanism for waking all
pollers on all fds when a filesystem node changes. To allow polling for
custom events, add a .poll callback that can override the default.
This is in preparation for pollable cgroup pressure files which have
per-fd trigger configurations.
Link: http://lkml.kernel.org/r/20190124211518.244221-2-surenb@google.com
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernfs_notify() does two notifications: poll and fsnotify. Originally,
both notifications were done from scheduled work context and all that
kernfs_notify() did was schedule the work.
This patch simply moves the poll notification from the scheduled work
handler to kernfs_notify(). The fsnotify notification still needs to be
done from scheduled work context because it can sleep (it needs to lock
a mutex).
If the poll notification is time critical (the notified thread needs to
wake as quickly as possible), it's better to do it from kernfs_notify()
directly. One example is calling sysfs_notify_dirent() from a hardware
interrupt handler to wake up a thread and handle the interrupt in user
space.
Signed-off-by: Radu Rendec <radu.rendec@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending
kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments.
The "simple" kernfs_create_file() and kernfs_create_dir() are left alone
and always create objects belonging to the global root.
When creating symlinks ownership (uid/gid) is taken from the target kernfs
object.
Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use new return type vm_fault_t for page_mkwrite and
fault handler. For now, this is just documenting that
the function returns a VM_FAULT value rather than an
errno. Once all instances are converted, vm_fault_t
will become a distinct type.
Reference id -> 1c8f422059 ("mm: change return type to
vm_fault_t")
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull misc vfs fixes from Al Viro.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
seq_file: fix incomplete reset on read from zero offset
kernfs: fix regression in kernfs_fop_write caused by wrong type
Commit b7ce40cff0 ("kernfs: cache atomic_write_len in
kernfs_open_file") changes type of local variable 'len' from ssize_t
to size_t. This change caused that the *ppos value is updated also
when the previous write callback failed.
Mentioned snippet:
...
len = ops->write(...); <- return value can be negative
...
if (len > 0) <- true here in this case
*ppos += len;
...
Fixes: b7ce40cff0 ("kernfs: cache atomic_write_len in kernfs_open_file")
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull block layer updates from Jens Axboe:
"This is the first pull request for 4.14, containing most of the code
changes. It's a quiet series this round, which I think we needed after
the churn of the last few series. This contains:
- Fix for a registration race in loop, from Anton Volkov.
- Overflow complaint fix from Arnd for DAC960.
- Series of drbd changes from the usual suspects.
- Conversion of the stec/skd driver to blk-mq. From Bart.
- A few BFQ improvements/fixes from Paolo.
- CFQ improvement from Ritesh, allowing idling for group idle.
- A few fixes found by Dan's smatch, courtesy of Dan.
- A warning fixup for a race between changing the IO scheduler and
device remova. From David Jeffery.
- A few nbd fixes from Josef.
- Support for cgroup info in blktrace, from Shaohua.
- Also from Shaohua, new features in the null_blk driver to allow it
to actually hold data, among other things.
- Various corner cases and error handling fixes from Weiping Zhang.
- Improvements to the IO stats tracking for blk-mq from me. Can
drastically improve performance for fast devices and/or big
machines.
- Series from Christoph removing bi_bdev as being needed for IO
submission, in preparation for nvme multipathing code.
- Series from Bart, including various cleanups and fixes for switch
fall through case complaints"
* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
kernfs: checking for IS_ERR() instead of NULL
drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
drbd: Fix allyesconfig build, fix recent commit
drbd: switch from kmalloc() to kmalloc_array()
drbd: abort drbd_start_resync if there is no connection
drbd: move global variables to drbd namespace and make some static
drbd: rename "usermode_helper" to "drbd_usermode_helper"
drbd: fix race between handshake and admin disconnect/down
drbd: fix potential deadlock when trying to detach during handshake
drbd: A single dot should be put into a sequence.
drbd: fix rmmod cleanup, remove _all_ debugfs entries
drbd: Use setup_timer() instead of init_timer() to simplify the code.
drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
drbd: new disk-option disable-write-same
drbd: Fix resource role for newly created resources in events2
drbd: mark symbols static where possible
drbd: Send P_NEG_ACK upon write error in protocol != C
drbd: add explicit plugging when submitting batches
drbd: change list_for_each_safe to while(list_first_entry_or_null)
drbd: introduce drbd_recv_header_maybe_unplug
...
The reference count in kernfs_node structure is treated like a rwsem by
using lockdep instrumentation code. The lockdep name, however, is still
"s_active" which is carried over from the old sysfs code. As s_active
is no longer the variable name, its use may confuse users on where the
lock is when it is reported by lockdep. So it is changed to "kn->count"
which is how this variable is normally referenced in kernfs code.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
inode number and generation can identify a kernfs node. We are going to
export the identification by exportfs operations, so put ino and
generation into a separate structure. It's convenient when later patches
use the identification.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When working on adding exportfs operations in kernfs, I found it's hard
to initialize dentry->d_fsdata in the exportfs operations. Looks there
is no way to do it without race condition. Look at the kernfs code
closely, there is no point to set dentry->d_fsdata. inode->i_private
already points to kernfs_node, and we can get inode from a dentry. So
this patch just delete the d_fsdata usage.
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Neel Natu