linux-toradex.git/include/linux/dcache.h, branch v4.4.65

vfs: add d_real_inode() helper

2016-07-27T16:47:33+00:00

commit a118084432d642eeccb961c7c8cc61525a941fcb upstream.

Needed by the following fix.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

vfs: add vfs_select_inode() helper

2016-05-19T00:06:48+00:00

commit 54d5ca871e72f2bb172ec9323497f01cd5091ec7 upstream.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fs: add file_dentry()

2016-04-20T06:42:12+00:00

commit d101a125954eae1d397adda94ca6319485a50493 upstream.

This series fixes bugs in nfs and ext4 due to 4bacc9c9234c ("overlayfs:
Make f_path always point to the overlay and f_inode to the underlay").

Regular files opened on overlayfs will result in the file being opened on
the underlying filesystem, while f_path points to the overlayfs
mount/dentry.

This confuses filesystems which get the dentry from struct file and assume
it's theirs.

Add a new helper, file_dentry() [*], to get the filesystem's own dentry
from the file.  This checks file->f_path.dentry->d_flags against
DCACHE_OP_REAL, and returns file->f_path.dentry if DCACHE_OP_REAL is not
set (this is the common, non-overlayfs case).

In the uncommon case it will call into overlayfs's ->d_real() to get the
underlying dentry, matching file_inode(file).

The reason we need to check against the inode is that if the file is copied
up while being open, d_real() would return the upper dentry, while the open
file comes from the lower dentry.

[*] If possible, it's better simply to use file_inode() instead.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Theodore Ts'o 
Tested-by: Goldwyn Rodrigues 
Reviewed-by: Trond Myklebust 
Cc: David Howells 
Cc: Al Viro 
Cc: Daniel Axtens 
Signed-off-by: Greg Kroah-Hartman

use ->d_seq to get coherency between ->d_inode and ->d_flags

2016-03-09T23:34:49+00:00

commit a528aca7f359f4b0b1d72ae406097e491a5ba9ea upstream.

Games with ordering and barriers are way too brittle.  Just
bump ->d_seq before and after updating ->d_inode and ->d_flags
type bits, so that verifying ->d_seq would guarantee they are
coherent.

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

include, lib: add __printf attributes to several function prototypes

2015-07-17T23:39:53+00:00

Using __printf attributes helps to detect several format string issues
at compile time (even though -Wformat-security is currently disabled in
Makefile).  For example it can detect when formatting a pointer as a
number, like the issue fixed in commit a3fa71c40f18 ("wl18xx: show
rx_frames_per_rates as an array as it really is"), or when the arguments
do not match the format string, c.f.  for example commit 5ce1aca81435
("reiserfs: fix __RASSERT format string").

To prevent similar bugs in the future, add a __printf attribute to every
function prototype which needs one in include/linux/ and lib/.  These
functions were mostly found by using gcc's -Wsuggest-attribute=format
flag.

Signed-off-by: Nicolas Iooss 
Cc: Greg Kroah-Hartman 
Cc: Felipe Balbi 
Cc: Joel Becker 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

make simple_positive() public

2015-06-23T22:02:01+00:00

Signed-off-by: Al Viro

overlayfs: Make f_path always point to the overlay and f_inode to the underlay

2015-06-19T07:19:32+00:00

Make file->f_path always point to the overlay dentry so that the path in
/proc/pid/fd is correct and to ensure that label-based LSMs have access to the
overlay as well as the underlay (path-based LSMs probably don't need it).

Using my union testsuite to set things up, before the patch I see:

	[root@andromeda union-testsuite]# bash 5 /a/foo107
	[root@andromeda union-testsuite]# stat /mnt/a/foo107
	...
	Device: 23h/35d Inode: 13381       Links: 1
	...
	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
	...
	Device: 23h/35d Inode: 13381       Links: 1
	...

After the patch:

	[root@andromeda union-testsuite]# bash 5 /mnt/a/foo107
	[root@andromeda union-testsuite]# stat /mnt/a/foo107
	...
	Device: 23h/35d Inode: 40346       Links: 1
	...
	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
	...
	Device: 23h/35d Inode: 40346       Links: 1
	...

Note the change in where /proc/$$/fd/5 points to in the ls command.  It was
pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107
(which is correct).

The inode accessed, however, is the lower layer.  The union layer is on device
25h/37d and the upper layer on 24h/36d.

Signed-off-by: David Howells 
Signed-off-by: Al Viro

VFS: Impose ordering on accesses of d_inode and d_flags

2015-04-15T19:05:28+00:00

Impose ordering on accesses of d_inode and d_flags to avoid the need to do
this:

	if (!dentry->d_inode || d_is_negative(dentry)) {

when this:

	if (d_is_negative(dentry)) {

should suffice.

This check is especially problematic if a dentry can have its type field set
to something other than DENTRY_MISS_TYPE when d_inode is NULL (as in
unionmount).

What we really need to do is stick a write barrier between setting d_inode and
setting d_flags and a read barrier between reading d_flags and reading
d_inode.

Signed-off-by: David Howells 
Signed-off-by: Al Viro

VFS: Add owner-filesystem positive/negative dentry checks

2015-04-15T19:04:42+00:00

Supply two functions to test whether a filesystem's own dentries are positive
or negative (d_really_is_positive() and d_really_is_negative()).

The problem is that the DCACHE_ENTRY_TYPE field of dentry->d_flags may be
overridden by the union part of a layered filesystem and isn't thus
necessarily indicative of the type of dentry.

Normally, this would involve a negative dentry (ie. ->d_inode == NULL) having
->d_layer.lower pointed to a lower layer dentry, DCACHE_PINNING_LOWER set and
the DCACHE_ENTRY_TYPE field set to something other than DCACHE_MISS_TYPE - but
it could also involve, say, a DCACHE_SPECIAL_TYPE being overridden to
DCACHE_WHITEOUT_TYPE if a 0,0 chardev is detected in the top layer.

However, inside a filesystem, when that fs is looking at its own dentries, it
probably wants to know if they are really negative or not - and doesn't care
about the fallthrough bits used by the union.

To this end, a filesystem should normally use d_really_is_positive/negative()
when looking at its own dentries rather than d_is_positive/negative() and
should use d_inode() to get at the inode.

Anyone looking at someone else's dentries (this includes pathwalk) should use
d_is_xxx() and d_backing_inode().

Signed-off-by: David Howells 
Signed-off-by: Al Viro

VFS: Split DCACHE_FILE_TYPE into regular and special types

2015-02-22T16:38:38+00:00

Split DCACHE_FILE_TYPE into DCACHE_REGULAR_TYPE (dentries representing regular
files) and DCACHE_SPECIAL_TYPE (representing blockdev, chardev, FIFO and
socket files).

d_is_reg() and d_is_special() are added to detect these subtypes and
d_is_file() is left as the union of the two.

This allows a number of places that use S_ISREG(dentry->d_inode->i_mode) to
use d_is_reg(dentry) instead.

Signed-off-by: David Howells 
Signed-off-by: Al Viro