linux-stable.git/fs/ext4/file.c, branch linux-4.3.y

ext4: start transaction before calling into DAX

2015-09-08T22:35:28+00:00

Jan Kara pointed out that in the case where we are writing to a hole, we
can end up with a lock inversion between the page lock and the journal
lock.  We can avoid this by starting the transaction in ext4 before
calling into DAX.  The journal lock nests inside the superblock
pagefault lock, so we have to duplicate that code from dax_fault, like
XFS does.

Signed-off-by: Matthew Wilcox 
Cc: Jan Kara 
Cc: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ext4: add ext4_get_block_dax()

2015-09-08T22:35:28+00:00

DAX wants different semantics from any currently-existing ext4 get_block
callback.  Unlike ext4_get_block_write(), it needs to honour the
'create' flag, and unlike ext4_get_block(), it needs to be able to
return unwritten extents.  So introduce a new ext4_get_block_dax() which
has those semantics.

We could also change ext4_get_block_write() to honour the 'create' flag,
but that might have consequences on other users that I do not currently
understand.

Signed-off-by: Matthew Wilcox 
Cc: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ext4: use ext4_get_block_write() for DAX

2015-09-08T22:35:28+00:00

DAX relies on the get_block function either zeroing newly allocated
blocks before they're findable by subsequent calls to get_block, or
marking newly allocated blocks as unwritten.  ext4_get_block() cannot
create unwritten extents, but ext4_get_block_write() can.

Signed-off-by: Matthew Wilcox 
Reported-by: Andy Rudoff 
Cc: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ext4: huge page fault support

2015-09-08T22:35:28+00:00

Use DAX to provide support for huge pages.

Signed-off-by: Matthew Wilcox 
Cc: Hillf Danton 
Cc: "Kirill A. Shutemov" 
Cc: Theodore Ts'o 
Cc: Jan Kara 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

dax: move DAX-related functions to a new header

2015-09-08T22:35:28+00:00

In order to handle the !CONFIG_TRANSPARENT_HUGEPAGES case, we need to
return VM_FAULT_FALLBACK from the inlined dax_pmd_fault(), which is
defined in linux/mm.h.  Given that we don't want to include 
in , the easiest solution is to move the DAX-related
functions to a new header, .  We could also have moved
VM_FAULT_* definitions to a new header, or a different header that isn't
quite such a boil-the-ocean header as , but this felt like
the best option.

Signed-off-by: Matthew Wilcox 
Cc: Hillf Danton 
Cc: "Kirill A. Shutemov" 
Cc: Theodore Ts'o 
Cc: Jan Kara 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'xfs-for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs

2015-07-01T03:16:08+00:00

Pul xfs updates from Dave Chinner:
 "There's a couple of small API changes to the core DAX code which
  required small changes to the ext2 and ext4 code bases, but otherwise
  everything is within the XFS codebase.

  This update contains:

   - A new sparse on-disk inode record format to allow small extents to
     be used for inode allocation when free space is fragmented.

   - DAX support.  This includes minor changes to the DAX core code to
     fix problems with lock ordering and bufferhead mapping abuse.

   - transaction commit interface cleanup

   - removal of various unnecessary XFS specific type definitions

   - cleanup and optimisation of freelist preparation before allocation

   - various minor cleanups

   - bug fixes for
	- transaction reservation leaks
	- incorrect inode logging in unwritten extent conversion
	- mmap lock vs freeze ordering
	- remote symlink mishandling
	- attribute fork removal issues"

* tag 'xfs-for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (49 commits)
  xfs: don't truncate attribute extents if no extents exist
  xfs: clean up XFS_MIN_FREELIST macros
  xfs: sanitise error handling in xfs_alloc_fix_freelist
  xfs: factor out free space extent length check
  xfs: xfs_alloc_fix_freelist() can use incore perag structures
  xfs: remove xfs_caddr_t
  xfs: use void pointers in log validation helpers
  xfs: return a void pointer from xfs_buf_offset
  xfs: remove inst_t
  xfs: remove __psint_t and __psunsigned_t
  xfs: fix remote symlinks on V5/CRC filesystems
  xfs: fix xfs_log_done interface
  xfs: saner xfs_trans_commit interface
  xfs: remove the flags argument to xfs_trans_cancel
  xfs: pass a boolean flag to xfs_trans_free_items
  xfs: switch remaining xfs_trans_dup users to xfs_trans_roll
  xfs: check min blks for random debug mode sparse allocations
  xfs: fix sparse inodes 32-bit compile failure
  xfs: add initial DAX support
  xfs: add DAX IO path support
  ...

dax: don't abuse get_block mapping for endio callbacks

2015-06-03T23:18:18+00:00

dax_fault() currently relies on the get_block callback to attach an
io completion callback to the mapping buffer head so that it can
run unwritten extent conversion after zeroing allocated blocks.

Instead of this hack, pass the conversion callback directly into
dax_fault() similar to the get_block callback. When the filesystem
allocates unwritten extents, it will set the buffer_unwritten()
flag, and hence the dax_fault code can call the completion function
in the contexts where it is necessary without overloading the
mapping buffer head.

Note: The changes to ext4 to use this interface are suspect at best.
In fact, the way ext4 did this end_io assignment in the first place
looks suspect because it only set a completion callback when there
wasn't already some other write() call taking place on the same
inode. The ext4 end_io code looks rather intricate and fragile with
all it's reference counting and passing to different contexts for
modification via inode private pointers that aren't protected by
locks...

Signed-off-by: Dave Chinner 
Acked-by: Jan Kara 
Signed-off-by: Dave Chinner

ext4 crypto: handle unexpected lack of encryption keys

2015-05-31T17:35:39+00:00

Fix up attempts by users to try to write to a file when they don't
have access to the encryption key.

Signed-off-by: Theodore Ts'o

ext4 crypto: reorganize how we store keys in the inode

2015-05-18T17:17:47+00:00

This is a pretty massive patch which does a number of different things:

1) The per-inode encryption information is now stored in an allocated
   data structure, ext4_crypt_info, instead of directly in the node.
   This reduces the size usage of an in-memory inode when it is not
   using encryption.

2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
   encryption structure instead.  This remove an unnecessary memory
   allocation and free for the fname_crypto_ctx as well as allowing us
   to reuse the ctfm in a directory for multiple lookups and file
   creations.

3) We also cache the inode's policy information in the ext4_crypt_info
   structure so we don't have to continually read it out of the
   extended attributes.

4) We now keep the keyring key in the inode's encryption structure
   instead of releasing it after we are done using it to derive the
   per-inode key.  This allows us to test to see if the key has been
   revoked; if it has, we prevent the use of the derived key and free
   it.

5) When an inode is released (or when the derived key is freed), we
   will use memset_explicit() to zero out the derived key, so it's not
   left hanging around in memory.  This implies that when a user logs
   out, it is important to first revoke the key, and then unlink it,
   and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
   release any decrypted pages and dcache entries from the system
   caches.

6) All this, and we also shrink the number of lines of code by around
   100.  :-)

Signed-off-by: Theodore Ts'o

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2015-04-19T21:26:31+00:00

Pull ext4 updates from Ted Ts'o:
 "A few bug fixes and add support for file-system level encryption in
  ext4"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (31 commits)
  ext4 crypto: enable encryption feature flag
  ext4 crypto: add symlink encryption
  ext4 crypto: enable filename encryption
  ext4 crypto: filename encryption modifications
  ext4 crypto: partial update to namei.c for fname crypto
  ext4 crypto: insert encrypted filenames into a leaf directory block
  ext4 crypto: teach ext4_htree_store_dirent() to store decrypted filenames
  ext4 crypto: filename encryption facilities
  ext4 crypto: implement the ext4 decryption read path
  ext4 crypto: implement the ext4 encryption write path
  ext4 crypto: inherit encryption policies on inode and directory create
  ext4 crypto: enforce context consistency
  ext4 crypto: add encryption key management facilities
  ext4 crypto: add ext4 encryption facilities
  ext4 crypto: add encryption policy and password salt support
  ext4 crypto: add encryption xattr support
  ext4 crypto: export ext4_empty_dir()
  ext4 crypto: add ext4 encryption Kconfig
  ext4 crypto: reserve codepoints used by the ext4 encryption feature
  ext4 crypto: add ext4_mpage_readpages()
  ...