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* Fix the regression created by "set S_DEAD on unlink()..." commitAl Viro2010-05-151-0/+4
| | | | | | | | | | | | | | | | | | | | | | | 1) i_flags simply doesn't work for mount/unlink race prevention; we may have many links to file and rm on one of those obviously shouldn't prevent bind on top of another later on. To fix it right way we need to mark _dentry_ as unsuitable for mounting upon; new flag (DCACHE_CANT_MOUNT) is protected by d_flags and i_mutex on the inode in question. Set it (with dont_mount(dentry)) in unlink/rmdir/etc., check (with cant_mount(dentry)) in places in namespace.c that used to check for S_DEAD. Setting S_DEAD is still needed in places where we used to set it (for directories getting killed), since we rely on it for readdir/rmdir race prevention. 2) rename()/mount() protection has another bogosity - we unhash the target before we'd checked that it's not a mountpoint. Fixed. 3) ancient bogosity in pivot_root() - we locked i_mutex on the right directory, but checked S_DEAD on the different (and wrong) one. Noticed and fixed. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* configfs: Rework configfs_depend_item() locking and make lockdep happyLouis Rilling2009-04-301-59/+47
| | | | | | | | | | | | | | | | | | | | | | configfs_depend_item() recursively locks all inodes mutex from configfs root to the target item, which makes lockdep unhappy. The purpose of this recursive locking is to ensure that the item tree can be safely parsed and that the target item, if found, is not about to leave. This patch reworks configfs_depend_item() locking using configfs_dirent_lock. Since configfs_dirent_lock protects all changes to the configfs_dirent tree, and protects tagging of items to be removed, this lock can be used instead of the inodes mutex lock chain. This needs that the check for dependents be done atomically with CONFIGFS_USET_DROPPING tagging. Now lockdep looks happy with configfs. [ Lifted the setting of s_type into configfs_new_dirent() to satisfy the atomic setting of CONFIGFS_USET_CREATING -- Joel ] Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Silence lockdep on mkdir() and rmdir()Louis Rilling2009-04-301-0/+90
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When attaching default groups (subdirs) of a new group (in mkdir() or in configfs_register()), configfs recursively takes inode's mutexes along the path from the parent of the new group to the default subdirs. This is needed to ensure that the VFS will not race with operations on these sub-dirs. This is safe for the following reasons: - the VFS allows one to lock first an inode and second one of its children (The lock subclasses for this pattern are respectively I_MUTEX_PARENT and I_MUTEX_CHILD); - from this rule any inode path can be recursively locked in descending order as long as it stays under a single mountpoint and does not follow symlinks. Unfortunately lockdep does not know (yet?) how to handle such recursion. I've tried to use Peter Zijlstra's lock_set_subclass() helper to upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know that we might recursively lock some of their descendant, but this usage does not seem to fit the purpose of lock_set_subclass() because it leads to several i_mutex locked with subclass I_MUTEX_PARENT by the same task. >From inside configfs it is not possible to serialize those recursive locking with a top-level one, because mkdir() and rmdir() are already called with inodes locked by the VFS. So using some mutex_lock_nest_lock() is not an option. I am proposing two solutions: 1) one that wraps recursive mutex_lock()s with lockdep_off()/lockdep_on(). 2) (as suggested earlier by Peter Zijlstra) one that puts the i_mutexes recursively locked in different classes based on their depth from the top-level config_group created. This induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the nesting of configfs default groups whenever lockdep is activated but this limit looks reasonably high. Unfortunately, this also isolates VFS operations on configfs default groups from the others and thus lowers the chances to detect locking issues. Nobody likes solution 1), which I can understand. This patch implements solution 2). However lockdep is still not happy with configfs_depend_item(). Next patch reworks the locking of configfs_depend_item() and finally makes lockdep happy. [ Note: This hides a few locking interactions with the VFS from lockdep. That was my big concern, because we like lockdep's protection. However, the current state always dumps a spurious warning. The locking is correct, so I tell people to ignore the warning and that we'll keep our eyes on the locking to make sure it stays correct. With this patch, we eliminate the warning. We do lose some of the lockdep protections, but this only means that we still have to keep our eyes on the locking. We're going to do that anyway. -- Joel ] Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* constify dentry_operations: configfsAl Viro2009-03-271-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Revert "configfs: Silence lockdep on mkdir(), rmdir() and ↵Mark Fasheh2009-02-041-59/+0
| | | | | | | | | | | | configfs_depend_item()" This reverts commit 0e0333429a6280e6eb3c98845e4eed90d5f8078a. I committed this by accident - Joel and Louis are working with the lockdep maintainer to provide a better solution than just turning lockdep off. Signed-off-by: Mark Fasheh <mfasheh@suse.com> Acked-by: <Joel Becker <joel.becker@oracle.com>
* configfs: Silence lockdep on mkdir(), rmdir() and configfs_depend_item()Joel Becker2009-02-021-0/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When attaching default groups (subdirs) of a new group (in mkdir() or in configfs_register()), configfs recursively takes inode's mutexes along the path from the parent of the new group to the default subdirs. This is needed to ensure that the VFS will not race with operations on these sub-dirs. This is safe for the following reasons: - the VFS allows one to lock first an inode and second one of its children (The lock subclasses for this pattern are respectively I_MUTEX_PARENT and I_MUTEX_CHILD); - from this rule any inode path can be recursively locked in descending order as long as it stays under a single mountpoint and does not follow symlinks. Unfortunately lockdep does not know (yet?) how to handle such recursion. I've tried to use Peter Zijlstra's lock_set_subclass() helper to upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know that we might recursively lock some of their descendant, but this usage does not seem to fit the purpose of lock_set_subclass() because it leads to several i_mutex locked with subclass I_MUTEX_PARENT by the same task. >From inside configfs it is not possible to serialize those recursive locking with a top-level one, because mkdir() and rmdir() are already called with inodes locked by the VFS. So using some mutex_lock_nest_lock() is not an option. I am proposing two solutions: 1) one that wraps recursive mutex_lock()s with lockdep_off()/lockdep_on(). 2) (as suggested earlier by Peter Zijlstra) one that puts the i_mutexes recursively locked in different classes based on their depth from the top-level config_group created. This induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the nesting of configfs default groups whenever lockdep is activated but this limit looks reasonably high. Unfortunately, this alos isolates VFS operations on configfs default groups from the others and thus lowers the chances to detect locking issues. This patch implements solution 1). Solution 2) looks better from lockdep's point of view, but fails with configfs_depend_item(). This needs to rework the locking scheme of configfs_depend_item() by removing the variable lock recursion depth, and I think that it's doable thanks to the configfs_dirent_lock. For now, let's stick to solution 1). Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Acked-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Consolidate locking around configfs_detach_prep() in ↵Louis Rilling2008-08-221-10/+7
| | | | | | | | | | | | | | | configfs_rmdir() It appears that configfs_rmdir() can protect configfs_detach_prep() retries with less calls to {spin,mutex}_{lock,unlock}, and a cleaner code. This patch does not change any behavior, except that it removes two useless lock/unlock pairs having nothing inside to protect and providing a useless barrier. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <Joel.Becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Pin configfs subsystems separately from new config_items.Joel Becker2008-07-311-9/+33
| | | | | | | | | | | | | | | | | | | | | configfs_mkdir() creates a new item by calling its parent's ->make_item/group() functions. Once that object is created, configfs_mkdir() calls try_module_get() on the new item's module. If it succeeds, the module owning the new item cannot be unloaded, and configfs is safe to reference the item. If the item and the subsystem it belongs to are part of the same module, the subsystem is also pinned. This is the common case. However, if the subsystem is made up of multiple modules, this may not pin the subsystem. Thus, it would be possible to unload the toplevel subsystem module while there is still a child item. Thus, we now try_module_get() the subsystem's module. This only really affects children of the toplevel subsystem group. Deeper children already have their parents pinned. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Fix open directory making rmdir() failLouis Rilling2008-07-311-1/+2
| | | | | | | | | | | | | | When checking for user-created elements under an item to be removed by rmdir(), configfs_detach_prep() counts fake configfs_dirents created by dir_open() as user-created and fails when finding one. It is however perfectly valid to remove a directory that is open. Simply make configfs_detach_prep() skip fake configfs_dirent, like it already does for attributes, and like detach_groups() does. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Lock new directory inodes before removing on cleanup after ↵Louis Rilling2008-07-311-19/+29
| | | | | | | | | | | | | | | | | failure Once a new configfs directory is created by configfs_attach_item() or configfs_attach_group(), a failure in the remaining initialization steps leads to removing a directory which inode the VFS may have already accessed. This commit adds the necessary inode locking to safely remove configfs directories while cleaning up after a failure. As an advantage, the locking rules of populate_groups() and detach_groups() become the same: the caller must have the group's inode mutex locked. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Prevent userspace from creating new entries under ↵Louis Rilling2008-07-311-5/+86
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | attaching directories process 1: process 2: configfs_mkdir("A") attach_group("A") attach_item("A") d_instantiate("A") populate_groups("A") mutex_lock("A") attach_group("A/B") attach_item("A") d_instantiate("A/B") mkdir("A/B/C") do_path_lookup("A/B/C", LOOKUP_PARENT) ok lookup_create("A/B/C") mutex_lock("A/B") ok configfs_mkdir("A/B/C") ok attach_group("A/C") attach_item("A/C") d_instantiate("A/C") populate_groups("A/C") mutex_lock("A/C") attach_group("A/C/D") attach_item("A/C/D") failure mutex_unlock("A/C") detach_groups("A/C") nothing to do mkdir("A/C/E") do_path_lookup("A/C/E", LOOKUP_PARENT) ok lookup_create("A/C/E") mutex_lock("A/C") ok configfs_mkdir("A/C/E") ok detach_item("A/C") d_delete("A/C") mutex_unlock("A") detach_groups("A") mutex_lock("A/B") detach_group("A/B") detach_groups("A/B") nothing since no _default_ group detach_item("A/B") mutex_unlock("A/B") d_delete("A/B") detach_item("A") d_delete("A") Two bugs: 1/ "A/B/C" and "A/C/E" are created, but never removed while their parent are removed in the end. The same could happen with symlink() instead of mkdir(). 2/ "A" and "A/C" inodes are not locked while detach_item() is called on them, which may probably confuse VFS. This commit fixes 1/, tagging new directories with CONFIGFS_USET_CREATING before building the inode and instantiating the dentry, and validating the whole group+default groups hierarchy in a second pass by clearing CONFIGFS_USET_CREATING. mkdir(), symlink(), lookup(), and dir_open() simply return -ENOENT if called in (or linking to) a directory tagged with CONFIGFS_USET_CREATING. This does not prevent userspace from calling stat() successfuly on such directories, but this prevents userspace from adding (children to | symlinking from/to | read/write attributes of | listing the contents of) not validated items. In other words, userspace will not interact with the subsystem on a new item until the new item creation completes correctly. It was first proposed to re-use CONFIGFS_USET_IN_MKDIR instead of a new flag CONFIGFS_USET_CREATING, but this generated conflicts when checking the target of a new symlink: a valid target directory in the middle of attaching a new user-created child item could be wrongly detected as being attached. 2/ is fixed by next commit. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Fix failing symlink() making rmdir() failLouis Rilling2008-07-311-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On a similar pattern as mkdir() vs rmdir(), a failing symlink() may make rmdir() fail for the symlink's parent and the symlink's target as well. failing symlink() making target's rmdir() fail: process 1: process 2: symlink("A/S" -> "B") allow_link() create_link() attach to "B" links list rmdir("B") detach_prep("B") error because of new link configfs_create_link("A", "S") error (eg -ENOMEM) failing symlink() making parent's rmdir() fail: process 1: process 2: symlink("A/D/S" -> "B") allow_link() create_link() attach to "B" links list configfs_create_link("A/D", "S") make_dirent("A/D", "S") rmdir("A") detach_prep("A") detach_prep("A/D") error because of "S" create("S") error (eg -ENOMEM) We cannot use the same solution as for mkdir() vs rmdir(), since rmdir() on the target cannot wait on the i_mutex of the new symlink's parent without risking a deadlock (with other symlink() or sys_rename()). Instead we define a global mutex protecting all configfs symlinks attachment, so that rmdir() can avoid the races above. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Fix symlink() to a removing itemLouis Rilling2008-07-311-7/+7
| | | | | | | | | | | | | | | | | | | | | | | The rule for configfs symlinks is that symlinks always point to valid config_items, and prevent the target from being removed. However, configfs_symlink() only checks that it can grab a reference on the target item, without ensuring that it remains alive until the symlink is correctly attached. This patch makes configfs_symlink() fail whenever the target is being removed, using the CONFIGFS_USET_DROPPING flag set by configfs_detach_prep() and protected by configfs_dirent_lock. This patch introduces a similar (weird?) behavior as with mkdir failures making rmdir fail: if symlink() races with rmdir() of the parent directory (or its youngest user-created ancestor if parent is a default group) or rmdir() of the target directory, and then fails in configfs_create(), this can make the racing rmdir() fail despite the concerned directory having no user-created entry (resp. no symlink pointing to it or one of its default groups) in the end. This behavior is fixed in later patches. Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* [PATCH] configfs: Include linux/err.h in linux/configfs.hJoel Becker2008-07-311-1/+1
| | | | | | | | We now use PTR_ERR() in the ->make_item() and ->make_group() operations. Folks including configfs.h need err.h. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
* configfs: Allow ->make_item() and ->make_group() to return detailed errors.Joel Becker2008-07-171-10/+15
| | | | | | | | | | | | | | | | | | The configfs operations ->make_item() and ->make_group() currently return a new item/group. A return of NULL signifies an error. Because of this, -ENOMEM is the only return code bubbled up the stack. Multiple folks have requested the ability to return specific error codes when these operations fail. This patch adds that ability by changing the ->make_item/group() ops to return ERR_PTR() values. These errors are bubbled up appropriately. NULL returns are changed to -ENOMEM for compatibility. Also updated are the in-kernel users of configfs. This is a rework of reverted commit 11c3b79218390a139f2d474ee1e983a672d5839a. Signed-off-by: Joel Becker <joel.becker@oracle.com>
* Revert "configfs: Allow ->make_item() and ->make_group() to return detailed ↵Joel Becker2008-07-171-6/+7
| | | | | | | | | errors." This reverts commit 11c3b79218390a139f2d474ee1e983a672d5839a. The code will move to PTR_ERR(). Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Allow ->make_item() and ->make_group() to return detailed errors.Joel Becker2008-07-141-7/+6
| | | | | | | | | | | | | | The configfs operations ->make_item() and ->make_group() currently return a new item/group. A return of NULL signifies an error. Because of this, -ENOMEM is the only return code bubbled up the stack. Multiple folks have requested the ability to return specific error codes when these operations fail. This patch adds that ability by changing the ->make_item/group() ops to return an int. Also updated are the in-kernel users of configfs. Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Fix failing mkdir() making racing rmdir() failLouis Rilling2008-07-141-10/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When fixing the rename() vs rmdir() deadlock, we stopped locking default groups' inodes in configfs_detach_prep(), letting racing mkdir() in default groups proceed concurrently. This enables races like below happen, which leads to a failing mkdir() making rmdir() fail, despite the group to remove having no user-created directory under it in the end. process A: process B: /* PWD=A/B */ mkdir("C") make_item("C") attach_group("C") rmdir("A") detach_prep("A") detach_prep("B") error because of "C" return -ENOTEMPTY attach_group("C/D") error (eg -ENOMEM) return -ENOMEM This patch prevents such scenarii by making rmdir() wait as long as detach_prep() fails because a racing mkdir() is in the middle of attach_group(). To achieve this, mkdir() sets a flag CONFIGFS_USET_IN_MKDIR in parent's configfs_dirent before calling attach_group(), and clears the flag once attach_group() is done. detach_prep() fails with -EAGAIN whenever the flag is hit and returns the guilty inode's mutex so that rmdir() can wait on it. Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Fix deadlock with racing rmdir() and rename()Louis Rilling2008-07-141-20/+25
| | | | | | | | | | | | | | | | | | | | | | This patch fixes the deadlock between racing sys_rename() and configfs_rmdir(). The idea is to avoid locking i_mutexes of default groups in configfs_detach_prep(), and rely instead on the new configfs_dirent_lock to protect against configfs_dirent's linkage mutations. To ensure that an mkdir() racing with rmdir() will not create new items in a to-be-removed default group, we make configfs_new_dirent() check for the CONFIGFS_USET_DROPPING flag right before linking the new dirent, and return error if the flag is set. This makes racing mkdir()/symlink()/dir_open() fail in places where errors could already happen, resp. in (attach_item()|attach_group())/create_link()/new_dirent(). configfs_depend() remains safe since it locks all the path from configfs root, and is thus mutually exclusive with rmdir(). An advantage of this is that now detach_groups() unconditionnaly takes the default groups i_mutex, which makes it more consistent with populate_groups(). Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Make configfs_new_dirent() return error code instead of NULLLouis Rilling2008-07-141-4/+5
| | | | | | | | This patch makes configfs_new_dirent return negative error code instead of NULL, which will be useful in the next patch to differentiate ENOMEM from ENOENT. Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Protect configfs_dirent s_links list mutationsLouis Rilling2008-07-141-2/+3
| | | | | | | | | | | | | | | | | Symlinks to a config_item are listed under its configfs_dirent s_links, but the list mutations are not protected by any common lock. This patch uses the configfs_dirent_lock spinlock to add the necessary protection. Note: we should also protect the list_empty() test in configfs_detach_prep() but 1/ the lock should not be released immediately because nothing would prevent the list from being filled after a successful list_empty() test, making the problem tricky, 2/ this will be solved by the rmdir() vs rename() deadlock bugfix. Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: Introduce configfs_dirent_lockLouis Rilling2008-07-141-1/+27
| | | | | | | | | | | | | | | | | | | | | | This patch introduces configfs_dirent_lock spinlock to protect configfs_dirent traversals against linkage mutations (add/del/move). This will allow configfs_detach_prep() to avoid locking i_mutexes. Locking rules for configfs_dirent linkage mutations are the same plus the requirement of taking configfs_dirent_lock. For configfs_dirent walking, one can either take appropriate i_mutex as before, or take configfs_dirent_lock. The spinlock could actually be a mutex, but the critical sections are either O(1) or should not be too long (default groups walking in last patch). ChangeLog: - Clarify the comment on configfs_dirent_lock usage - Move sd->s_element init before linking the new dirent - In lseek(), do not release configfs_dirent_lock before the dirent is relinked. Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
* configfs: dir.c fix possible recursive lockingJoonwoo Park2008-01-251-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | configfs_register_subsystem() with default_groups triggers recursive locking. it seems that mutex_lock_nested is needed. ============================================= [ INFO: possible recursive locking detected ] 2.6.24-rc6 #141 --------------------------------------------- swapper/1 is trying to acquire lock: (&sb->s_type->i_mutex_key#3){--..}, at: [<c40ca76f>] configfs_attach_group+0x4f/0x190 but task is already holding lock: (&sb->s_type->i_mutex_key#3){--..}, at: [<c40ca9d5>] configfs_register_subsystem+0x55/0x130 other info that might help us debug this: 1 lock held by swapper/1: #0: (&sb->s_type->i_mutex_key#3){--..}, at: [<c40ca9d5>] configfs_register_subsystem+0x55/0x130 stack backtrace: Pid: 1, comm: swapper Not tainted 2.6.24-rc6 #141 [<c40053ba>] show_trace_log_lvl+0x1a/0x30 [<c4005e82>] show_trace+0x12/0x20 [<c400687e>] dump_stack+0x6e/0x80 [<c404ec72>] __lock_acquire+0xe62/0x1120 [<c404efb2>] lock_acquire+0x82/0xa0 [<c43fdad8>] mutex_lock_nested+0x98/0x2e0 [<c40ca76f>] configfs_attach_group+0x4f/0x190 [<c40caa46>] configfs_register_subsystem+0xc6/0x130 [<c45c8186>] init_netconsole+0x2b6/0x300 [<c45a75f2>] kernel_init+0x142/0x320 [<c4004fb3>] kernel_thread_helper+0x7/0x14 ======================= Signed-off-by: Joonwoo Park <joonwpark81@gmail.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* r/o bind mounts: filesystem helpers for custom 'struct file'sDave Hansen2007-10-171-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Why do we need r/o bind mounts? This feature allows a read-only view into a read-write filesystem. In the process of doing that, it also provides infrastructure for keeping track of the number of writers to any given mount. This has a number of uses. It allows chroots to have parts of filesystems writable. It will be useful for containers in the future because users may have root inside a container, but should not be allowed to write to somefilesystems. This also replaces patches that vserver has had out of the tree for several years. It allows security enhancement by making sure that parts of your filesystem read-only (such as when you don't trust your FTP server), when you don't want to have entire new filesystems mounted, or when you want atime selectively updated. I've been using the following script to test that the feature is working as desired. It takes a directory and makes a regular bind and a r/o bind mount of it. It then performs some normal filesystem operations on the three directories, including ones that are expected to fail, like creating a file on the r/o mount. This patch: Some filesystems forego the vfs and may_open() and create their own 'struct file's. This patch creates a couple of helper functions which can be used by these filesystems, and will provide a unified place which the r/o bind mount code may patch. Also, rename an existing, static-scope init_file() to a less generic name. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* configfs: config item dependancies.Joel Becker2007-07-101-0/+244
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sometimes other drivers depend on particular configfs items. For example, ocfs2 mounts depend on a heartbeat region item. If that region item is removed with rmdir(2), the ocfs2 mount must BUG or go readonly. Not happy. This provides two additional API calls: configfs_depend_item() and configfs_undepend_item(). A client driver can call configfs_depend_item() on an existing item to tell configfs that it is depended on. configfs will then return -EBUSY from rmdir(2) for that item. When the item is no longer depended on, the client driver calls configfs_undepend_item() on it. These API cannot be called underneath any configfs callbacks, as they will conflict. They can block and allocate. A client driver probably shouldn't calling them of its own gumption. Rather it should be providing an API that external subsystems call. How does this work? Imagine the ocfs2 mount process. When it mounts, it asks for a heart region item. This is done via a call into the heartbeat code. Inside the heartbeat code, the region item is looked up. Here, the heartbeat code calls configfs_depend_item(). If it succeeds, then heartbeat knows the region is safe to give to ocfs2. If it fails, it was being torn down anyway, and heartbeat can gracefully pass up an error. [ Fixed some bad whitespace in configfs.txt. --Mark ] Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: accessing item hierarchy during rmdir(2)Joel Becker2007-07-101-1/+28
| | | | | | | | | | | | | | | | Add a notification callback, ops->disconnect_notify(). It has the same prototype as ->drop_item(), but it will be called just before the item linkage is broken. This way, configfs users who want to do work while the object is still in the heirarchy have a chance. Client drivers will still need to config_item_put() in their ->drop_item(), if they implement it. They need do nothing in ->disconnect_notify(). They don't have to provide it if they don't care. But someone who wants to be notified before ci_parent is set to NULL can now be notified. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: Convert subsystem semaphore to mutexJoel Becker2007-07-101-8/+8
| | | | | | | | | | | | | | Convert the su_sem member of struct configfs_subsystem to a struct mutex, as that's what it is. Also convert all the users and update Documentation/configfs.txt and Documentation/configfs_example.c accordingly. [ Conflict in fs/dlm/config.c with commit 3168b0780d06ace875696f8a648d04d6089654e5 manually resolved. --Mark ] Inspired-by: Satyam Sharma <ssatyam@cse.iitk.ac.in> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: add missing mutex_unlock()Joel Becker2007-03-141-15/+12
| | | | | | | | | | d_alloc() failure in configfs_register_subsystem() would fail to unlock the mutex taken above. Reorganize the exit path to ensure the unlock happens. Reported-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] mark struct inode_operations const 1Arjan van de Ven2007-02-121-1/+1
| | | | | | | | | | | Many struct inode_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc().Robert P. J. Day2007-02-111-2/+1
| | | | | | | | | | | | | | | | | | | | | | Replace appropriate pairs of "kmem_cache_alloc()" + "memset(0)" with the corresponding "kmem_cache_zalloc()" call. Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Andi Kleen <ak@muc.de> Cc: Roland McGrath <roland@redhat.com> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Greg KH <greg@kroah.com> Acked-by: Joel Becker <Joel.Becker@oracle.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Jan Kara <jack@ucw.cz> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] configfs: change uses of f_{dentry, vfsmnt} to use f_pathJosef "Jeff" Sipek2006-12-081-5/+5
| | | | | | | | | Change all the uses of f_{dentry,vfsmnt} to f_path.{dentry,mnt} in the configfs filesystem. Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* configfs: make configfs_dirent_exists() staticAdrian Bunk2006-12-011-2/+2
| | | | | | | | This patch makes the needlessly global configfs_dirent_exists() static. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: mutex_lock_nested() fixMark Fasheh2006-12-011-2/+3
| | | | | | | configfs_unregister_subsystem() nests a pair of inode i_mutex acquisitions, and thus needs annotation via mutex_lock_nested(). Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] r/o bind mount prepwork: inc_nlink() helperDave Hansen2006-10-011-2/+2
| | | | | | | | | | | This is mostly included for parity with dec_nlink(), where we will have some more hooks. This one should stay pretty darn straightforward for now. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Acked-by: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* configfs: Prevent duplicate subsystem names.Joel Becker2006-09-201-2/+30
| | | | | | | | | | | For all child objects, creation comes through mkdir(2), so duplicate names are prevented. Subsystems, though, are registered by client drivers at init_module()/__init time. This patch prevents duplicate subsystem names. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: Clear up a few extra spaces where there should be TABs.Joel Becker2006-06-291-3/+3
| | | | | Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] fs: use list_move()Akinobu Mita2006-06-261-4/+2
| | | | | | | | | | | | | | | | This patch converts the combination of list_del(A) and list_add(A, B) to list_move(A, B) under fs/. Cc: Ian Kent <raven@themaw.net> Acked-by: Joel Becker <joel.becker@oracle.com> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: Hans Reiser <reiserfs-dev@namesys.com> Cc: Urban Widmark <urban@teststation.com> Acked-by: David Howells <dhowells@redhat.com> Acked-by: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* configfs: configfs_mkdir() failed to cleanup linkage.Joel Becker2006-05-171-32/+72
| | | | | | | | | If configfs_mkdir() errored in certain ways after the parent<->child linkage was already created, it would not undo the linkage. Also, comment the reference counting for clarity. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* configfs: Fix a reference leak in configfs_mkdir().Joel Becker2006-05-171-11/+26
| | | | | | | | configfs_mkdir() failed to release the working parent reference in most exit paths. Also changed the exit path for readability. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] Bogus NULL pointer check in fs/configfs/dir.cEric Sesterhenn2006-04-101-1/+1
| | | | | | | | We check the "group" pointer after we dereference it. This check is bogus, as it cannot be NULL coming in. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] Make most file operations structs in fs/ constArjan van de Ven2006-03-281-1/+1
| | | | | | | | | | | | | | This is a conversion to make the various file_operations structs in fs/ const. Basically a regexp job, with a few manual fixups The goal is both to increase correctness (harder to accidentally write to shared datastructures) and reducing the false sharing of cachelines with things that get dirty in .data (while .rodata is nicely read only and thus cache clean) Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* configfs: Add permission and ownership to configfs objects.Joel Becker2006-02-031-10/+26
| | | | | | | | | | configfs always made item and attribute ownership root.root and permissions based on a umask of 022. Add ->setattr() to allow chown(2)/chmod(2), and persist the changes for the lifetime of the items and attributes. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
* [PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_semJes Sorensen2006-01-091-27/+27
| | | | | | | | | | | | | This patch converts the inode semaphore to a mutex. I have tested it on XFS and compiled as much as one can consider on an ia64. Anyway your luck with it might be different. Modified-by: Ingo Molnar <mingo@elte.hu> (finished the conversion) Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] configfs: User-driven configuration filesystemJoel Becker2006-01-031-0/+1102
Configfs, a file system for userspace-driven kernel object configuration. The OCFS2 stack makes extensive use of this for propagation of cluster configuration information into kernel. Signed-off-by: Joel Becker <joel.becker@oracle.com>
generated by cgit v1.1 at 2024-12-28 09:43:57 +0000