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  1. 15 7月, 2008 6 次提交
    • J
      configfs: Allow ->make_item() and ->make_group() to return detailed errors. · 11c3b792
      由 Joel Becker 提交于 
      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: NJoel Becker <joel.becker@oracle.com>
      11c3b792
    • L
      configfs: Fix failing mkdir() making racing rmdir() fail · 6d8344ba
      由 Louis Rilling 提交于 
      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: NLouis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      6d8344ba
    • L
      configfs: Fix deadlock with racing rmdir() and rename() · b3e76af8
      由 Louis Rilling 提交于 
      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: NLouis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      b3e76af8
    • L
      configfs: Make configfs_new_dirent() return error code instead of NULL · 107ed40b
      由 Louis Rilling 提交于 
      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: NLouis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      107ed40b
    • L
      configfs: Protect configfs_dirent s_links list mutations · 5301a77d
      由 Louis Rilling 提交于 
      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: NLouis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      5301a77d
    • L
      configfs: Introduce configfs_dirent_lock · 6f610764
      由 Louis Rilling 提交于 
      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: NLouis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      6f610764
  3. 26 1月, 2008 1 次提交
    • J
      configfs: dir.c fix possible recursive locking · ba611edf
      由 Joonwoo Park 提交于 
      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: NJoonwoo Park <joonwpark81@gmail.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
      ba611edf
  5. 17 10月, 2007 1 次提交
    • D
      r/o bind mounts: filesystem helpers for custom 'struct file's · ce8d2cdf
      由 Dave Hansen 提交于 
      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: NDave Hansen <haveblue@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ce8d2cdf
  7. 11 7月, 2007 3 次提交
    • J
      configfs: config item dependancies. · 631d1feb
      由 Joel Becker 提交于 
      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: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
      631d1feb
    • J
      configfs: accessing item hierarchy during rmdir(2) · 299894cc
      由 Joel Becker 提交于 
      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: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
      299894cc
    • J
      configfs: Convert subsystem semaphore to mutex · e6bd07ae
      由 Joel Becker 提交于 
      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
  3168b078 manually resolved. --Mark ]
Inspired-by: NSatyam Sharma <ssatyam@cse.iitk.ac.in>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
      e6bd07ae
  9. 15 3月, 2007 1 次提交
  11. 13 2月, 2007 1 次提交
  13. 12 2月, 2007 1 次提交
  15. 09 12月, 2006 1 次提交
  17. 02 12月, 2006 2 次提交
  19. 01 10月, 2006 1 次提交
  21. 21 9月, 2006 1 次提交
  23. 30 6月, 2006 1 次提交
  25. 27 6月, 2006 1 次提交
  27. 18 5月, 2006 2 次提交
  29. 11 4月, 2006 1 次提交
  31. 29 3月, 2006 1 次提交
  33. 04 2月, 2006 1 次提交
  35. 10 1月, 2006 1 次提交
  37. 04 1月, 2006 1 次提交