linux-toradex.git/fs/nilfs2/super.c, branch v3.2.55

nilfs2: fix deadlock issue between chcp and thaw ioctls

2012-08-09T23:25:02+00:00

commit 572d8b3945a31bee7c40d21556803e4807fd9141 upstream.

An fs-thaw ioctl causes deadlock with a chcp or mkcp -s command:

 chcp            D ffff88013870f3d0     0  1325   1324 0x00000004
 ...
 Call Trace:
   nilfs_transaction_begin+0x11c/0x1a0 [nilfs2]
   wake_up_bit+0x20/0x20
   copy_from_user+0x18/0x30 [nilfs2]
   nilfs_ioctl_change_cpmode+0x7d/0xcf [nilfs2]
   nilfs_ioctl+0x252/0x61a [nilfs2]
   do_page_fault+0x311/0x34c
   get_unmapped_area+0x132/0x14e
   do_vfs_ioctl+0x44b/0x490
   __set_task_blocked+0x5a/0x61
   vm_mmap_pgoff+0x76/0x87
   __set_current_blocked+0x30/0x4a
   sys_ioctl+0x4b/0x6f
   system_call_fastpath+0x16/0x1b
 thaw            D ffff88013870d890     0  1352   1351 0x00000004
 ...
 Call Trace:
   rwsem_down_failed_common+0xdb/0x10f
   call_rwsem_down_write_failed+0x13/0x20
   down_write+0x25/0x27
   thaw_super+0x13/0x9e
   do_vfs_ioctl+0x1f5/0x490
   vm_mmap_pgoff+0x76/0x87
   sys_ioctl+0x4b/0x6f
   filp_close+0x64/0x6c
   system_call_fastpath+0x16/0x1b

where the thaw ioctl deadlocked at thaw_super() when called while chcp was
waiting at nilfs_transaction_begin() called from
nilfs_ioctl_change_cpmode().  This deadlock is 100% reproducible.

This is because nilfs_ioctl_change_cpmode() first locks sb->s_umount in
read mode and then waits for unfreezing in nilfs_transaction_begin(),
whereas thaw_super() locks sb->s_umount in write mode.  The locking of
sb->s_umount here was intended to make snapshot mounts and the downgrade
of snapshots to checkpoints exclusive.

This fixes the deadlock issue by replacing the sb->s_umount usage in
nilfs_ioctl_change_cpmode() with a dedicated mutex which protects snapshot
mounts.

Signed-off-by: Ryusuke Konishi 
Cc: Fernando Luis Vazquez Cao 
Tested-by: Ryusuke Konishi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

nilfs2: always set back pointer to host inode in mapping->host

2011-05-10T13:21:57+00:00

In the current nilfs, page cache for btree nodes and meta data files
do not set a valid back pointer to the host inode in mapping->host.

This will change it so that every address space in nilfs uses
mapping->host to hold its host inode.

Signed-off-by: Ryusuke Konishi

nilfs2: implement resize ioctl

2011-05-10T13:21:46+00:00

This adds resize ioctl which makes online resize possible.

Signed-off-by: Ryusuke Konishi

nilfs2: add routine to move secondary super block

2011-05-10T13:21:45+00:00

After resizing the filesystem, the secondary super block must be moved
to a new location.  This adds a helper function for this.

Signed-off-by: Ryusuke Konishi

nilfs2: get rid of nilfs_sb_info structure

2011-03-09T02:54:26+00:00

This directly uses sb->s_fs_info to keep a nilfs filesystem object and
fully removes the intermediate nilfs_sb_info structure.  With this
change, the hierarchy of on-memory structures of nilfs will be
simplified as follows:

Before:
  super_block
       -> nilfs_sb_info
             -> the_nilfs
                   -> cptree --+-> nilfs_root (current file system)
                               +-> nilfs_root (snapshot A)
                               +-> nilfs_root (snapshot B)
                               :
             -> nilfs_sc_info (log writer structure)
After:
  super_block
       -> the_nilfs
             -> cptree --+-> nilfs_root (current file system)
                         +-> nilfs_root (snapshot A)
                         +-> nilfs_root (snapshot B)
                         :
             -> nilfs_sc_info (log writer structure)

The reason why we didn't design so from the beginning is because the
initial shape also differed from the above.  The early hierachy was
composed of "per-mount-point" super_block -> nilfs_sb_info pairs and a
shared nilfs object.  On the kernel 2.6.37, it was changed to the
current shape in order to unify super block instances into one per
device, and this cleanup became applicable as the result.

Signed-off-by: Ryusuke Konishi

nilfs2: use sb instance instead of nilfs_sb_info struct

2011-03-09T02:05:08+00:00

This replaces sbi uses with direct reference to sb instance.

Signed-off-by: Ryusuke Konishi

nilfs2: move next generation counter into nilfs object

2011-03-09T02:05:08+00:00

Moves s_next_generation counter and a spinlock protecting it to nilfs
object from nilfs_sb_info structure.

Signed-off-by: Ryusuke Konishi

nilfs2: move s_inode_lock and s_dirty_files into nilfs object

2011-03-09T02:05:07+00:00

Moves s_inode_lock spinlock and s_dirty_files list to nilfs object
from nilfs_sb_info structure.

Signed-off-by: Ryusuke Konishi

nilfs2: move parameters on nilfs_sb_info into nilfs object

2011-03-09T02:05:07+00:00

This moves four parameter variables on nilfs_sb_info s_resuid,
s_resgid, s_interval and s_watermark to the nilfs object.

Signed-off-by: Ryusuke Konishi

nilfs2: move mount options to nilfs object

2011-03-09T02:05:07+00:00

This moves mount_opt local variable to nilfs object from nilfs_sb_info
struct.

Signed-off-by: Ryusuke Konishi