linux.git/fs/open.c, branch v2.6.15

[PATCH] add a file_permission helper

2005-11-09T15:55:59+00:00

A few more callers of permission() just want to check for a different access
pattern on an already open file.  This patch adds a wrapper for permission()
that takes a file in preparation of per-mount read-only support and to clean
up the callers a little.  The helper is not intended for new code, everything
without the interface set in stone should use vfs_permission()

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] add a vfs_permission helper

2005-11-09T15:55:58+00:00

Most permission() calls have a struct nameidata * available.  This helper
takes that as an argument and thus makes sure we pass it down for lookup
intents and prepares for per-mount read-only support where we need a struct
vfsmount for checking whether a file is writeable.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] VFS: pass file pointer to filesystem from ftruncate()

2005-11-07T15:53:42+00:00

This patch extends the iattr structure with a file pointer memeber, and adds
an ATTR_FILE validity flag for this member.

This is set if do_truncate() is invoked from ftruncate() or from
do_coredump().

The change is source and binary compatible.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] memory leak in dentry_open()

2005-11-07T15:53:39+00:00

There is a memory leak possible in dentry_open().  If get_empty_filp()
fails, then the references to dentry and mnt need to be released.  The
attached patch adds the calls to dput() and mntput() to release these two
references.

Signed-off-by: Peter Staubach 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

VFS: Allow the filesystem to return a full file pointer on open intent

2005-10-18T21:20:16+00:00

 This is needed by NFSv4 for atomicity reasons: our open command is in
 fact a lookup+open, so we need to be able to propagate open context
 information from lookup() into the resulting struct file's
 private_data field.

 Signed-off-by: Trond Myklebust

[PATCH] open returns ENFILE but creates file anyway

2005-09-13T15:22:28+00:00

When open(O_CREAT) is called and the error, ENFILE, is returned, the file
may be created anyway.  This is counter intuitive, against the SUS V3
specification, and may cause applications to misbehave if they are not
coded correctly to handle this semantic.  The SUS V3 specification
explicitly states "No files shall be created or modified if the function
returns -1.".

The error, ENFILE, is used to indicate the system wide open file table is
full and no more file structs can be allocated.

This is due to an ordering problem.  The entry in the directory is created
before the file struct is allocated.  If the allocation for the file struct
fails, then the system call must return an error, but the directory entry
was already created and can not be safely removed.

The solution to this situation is relatively easy.  The file struct should
be allocated before the directory entry is created.  If the allocation
fails, then the error can be returned directly.  If the creation of the
directory entry fails, then the file struct can be easily freed.

Signed-off-by: Peter Staubach 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] files: files struct with RCU

2005-09-09T20:57:55+00:00

Patch to eliminate struct files_struct.file_lock spinlock on the reader side
and use rcu refcounting rcuref_xxx api for the f_count refcounter.  The
updates to the fdtable are done by allocating a new fdtable structure and
setting files->fdt to point to the new structure.  The fdtable structure is
protected by RCU thereby allowing lock-free lookup.  For fd arrays/sets that
are vmalloced, we use keventd to free them since RCU callbacks can't sleep.  A
global list of fdtable to be freed is not scalable, so we use a per-cpu list.
If keventd is already handling the current cpu's work, we use a timer to defer
queueing of that work.

Since the last publication, this patch has been re-written to avoid using
explicit memory barriers and use rcu_assign_pointer(), rcu_dereference()
premitives instead.  This required that the fd information is kept in a
separate structure (fdtable) and updated atomically.

Signed-off-by: Dipankar Sarma 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] files: break up files struct

2005-09-09T20:57:55+00:00

In order for the RCU to work, the file table array, sets and their sizes must
be updated atomically.  Instead of ensuring this through too many memory
barriers, we put the arrays and their sizes in a separate structure.  This
patch takes the first step of putting the file table elements in a separate
structure fdtable that is embedded withing files_struct.  It also changes all
the users to refer to the file table using files_fdtable() macro.  Subsequent
applciation of RCU becomes easier after this.

Signed-off-by: Dipankar Sarma 
Signed-Off-By: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] remove duplicated sys_open32() code from 64bit archs

2005-09-07T23:57:43+00:00

64 bit architectures all implement their own compatibility sys_open(),
when in fact the difference is simply not forcing the O_LARGEFILE
flag.  So use the a common function instead.

Signed-off-by: Miklos Szeredi 
Cc: 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] inotify

2005-07-13T03:38:38+00:00

inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:

        * dnotify requires the opening of one fd per each directory
          that you intend to watch. This quickly results in too many
          open files and pins removable media, preventing unmount.
        * dnotify is directory-based. You only learn about changes to
          directories. Sure, a change to a file in a directory affects
          the directory, but you are then forced to keep a cache of
          stat structures.
        * dnotify's interface to user-space is awful.  Signals?

inotify provides a more usable, simple, powerful solution to file change
notification:

        * inotify's interface is a system call that returns a fd, not SIGIO.
	  You get a single fd, which is select()-able.
        * inotify has an event that says "the filesystem that the item
          you were watching is on was unmounted."
        * inotify can watch directories or files.

Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.

See Documentation/filesystems/inotify.txt.

Signed-off-by: Robert Love 
Cc: John McCutchan 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds