linux.git/fs/open.c, branch v2.6.26-rc7

[PATCH] split linux/file.h

2008-05-01T17:08:16+00:00

Initial splitoff of the low-level stuff; taken to fdtable.h

Signed-off-by: Al Viro

xip: support non-struct page backed memory

2008-04-28T15:58:23+00:00

Convert XIP to support non-struct page backed memory, using VM_MIXEDMAP for
the user mappings.

This requires the get_xip_page API to be changed to an address based one.
Improve the API layering a little bit too, while we're here.

This is required in order to support XIP filesystems on memory that isn't
backed with struct page (but memory with struct page is still supported too).

Signed-off-by: Nick Piggin 
Acked-by: Carsten Otte 
Cc: Jared Hulbert 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] r/o bind mounts: debugging for missed calls

2008-04-19T04:29:28+00:00

There have been a few oopses caused by 'struct file's with NULL f_vfsmnts.
There was also a set of potentially missed mnt_want_write()s from
dentry_open() calls.

This patch provides a very simple debugging framework to catch these kinds of
bugs.  It will WARN_ON() them, but should stop us from having any oopses or
mnt_writer count imbalances.

I'm quite convinced that this is a good thing because it found bugs in the
stuff I was working on as soon as I wrote it.

[hch: made it conditional on a debug option.
      But it's still a little bit too ugly]

[hch: merged forced remount r/o fix from Dave and akpm's fix for the fix]

Signed-off-by: Dave Hansen 
Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

[PATCH] r/o bind mounts: make access() use new r/o helper

2008-04-19T04:29:26+00:00

It is OK to let access() go without using a mnt_want/drop_write() pair because
it doesn't actually do writes to the filesystem, and it is inherently racy
anyway.  This is a rare case when it is OK to use __mnt_is_readonly()
directly.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

[PATCH] r/o bind mounts: write counts for truncate()

2008-04-19T04:29:25+00:00

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Al Viro

[PATCH] r/o bind mounts: elevate write count for chmod/chown callers

2008-04-19T04:29:25+00:00

chown/chmod,etc...  don't call permission in the same way that the normal
"open for write" calls do.  They still write to the filesystem, so bump the
write count during these operations.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

[PATCH] r/o bind mounts: elevate write count for open()s

2008-04-19T04:29:25+00:00

This is the first really tricky patch in the series.  It elevates the writer
count on a mount each time a non-special file is opened for write.

We used to do this in may_open(), but Miklos pointed out that __dentry_open()
is used as well to create filps.  This will cover even those cases, while a
call in may_open() would not have.

There is also an elevated count around the vfs_create() call in open_namei().
See the comments for more details, but we need this to fix a 'create, remount,
fail r/w open()' race.

Some filesystems forego the use of normal vfs calls to create
struct files.   Make sure that these users elevate the mnt
writer count because they will get __fput(), and we need
to make sure they're balanced.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

[PATCH] merge open_namei() and do_filp_open()

2008-04-19T04:25:32+00:00

open_namei() will, in the future, need to take mount write counts
over its creation and truncation (via may_open()) operations.  It
needs to keep these write counts until any potential filp that is
created gets __fput()'d.

This gets complicated in the error handling and becomes very murky
as to how far open_namei() actually got, and whether or not that
mount write count was taken.  That makes it a bad interface.

All that the current do_filp_open() really does is allocate the
nameidata on the stack, then call open_namei().

So, this merges those two functions and moves filp_open() over
to namei.c so it can be close to its buddy: do_filp_open().  It
also gets a kerneldoc comment in the process.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Dave Hansen 
Signed-off-by: Al Viro

[PATCH] do namei_flags calculation inside open_namei()

2008-04-19T04:25:31+00:00

My end goal here is to make sure all users of may_open()
return filps.  This will ensure that we properly release
mount write counts which were taken for the filp in
may_open().

This patch moves the sys_open flags to namei flags
calculation into fs/namei.c.  We'll shortly be moving
the nameidata_to_filp() calls into namei.c, and this
gets the sys_open flags to a place where we can get
at them when we need them.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Al Viro

asmlinkage_protect replaces prevent_tail_call

2008-04-11T00:28:26+00:00

The prevent_tail_call() macro works around the problem of the compiler
clobbering argument words on the stack, which for asmlinkage functions
is the caller's (user's) struct pt_regs.  The tail/sibling-call
optimization is not the only way that the compiler can decide to use
stack argument words as scratch space, which we have to prevent.
Other optimizations can do it too.

Until we have new compiler support to make "asmlinkage" binding on the
compiler's own use of the stack argument frame, we have work around all
the manifestations of this issue that crop up.

More cases seem to be prevented by also keeping the incoming argument
variables live at the end of the function.  This makes their original
stack slots attractive places to leave those variables, so the compiler
tends not clobber them for something else.  It's still no guarantee, but
it handles some observed cases that prevent_tail_call() did not.

Signed-off-by: Roland McGrath 
Signed-off-by: Linus Torvalds