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Merge branch 'cross-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Browse source 
Pull renameat2 system call from Miklos Szeredi:
 "This adds a new syscall, renameat2(), which is the same as renameat()
  but with a flags argument.

  The purpose of extending rename is to add cross-rename, a symmetric
  variant of rename, which exchanges the two files.  This allows
  interesting things, which were not possible before, for example
  atomically replacing a directory tree with a symlink, etc...  This
  also allows overlayfs and friends to operate on whiteouts atomically.

  Andy Lutomirski also suggested a "noreplace" flag, which disables the
  overwriting behavior of rename.

  These two flags, RENAME_EXCHANGE and RENAME_NOREPLACE are only
  implemented for ext4 as an example and for testing"

* 'cross-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ext4: add cross rename support
  ext4: rename: split out helper functions
  ext4: rename: move EMLINK check up
  ext4: rename: create ext4_renament structure for local vars
  vfs: add cross-rename
  vfs: lock_two_nondirectories: allow directory args
  security: add flags to rename hooks
  vfs: add RENAME_NOREPLACE flag
  vfs: add renameat2 syscall
  vfs: rename: use common code for dir and non-dir
  vfs: rename: move d_move() up
  vfs: add d_is_dir()
This commit is contained in:
Linus Torvalds 2014-04-04 14:03:05 -07:00
commit 7df934526c
17 changed files with 643 additions and 313 deletions
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6
Documentation/filesystems/Locking
View file

@ -47,6 +47,8 @@ prototypes:
int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
int (*rename) (struct inode *, struct dentry *,
struct inode *, struct dentry *);
int (*rename2) (struct inode *, struct dentry *,
struct inode *, struct dentry *, unsigned int);
int (*readlink) (struct dentry *, char __user *,int);
void * (*follow_link) (struct dentry *, struct nameidata *);
void (*put_link) (struct dentry *, struct nameidata *, void *);
@ -78,6 +80,7 @@ mkdir: yes
unlink: yes (both)
rmdir: yes (both) (see below)
rename: yes (all) (see below)
rename2: yes (all) (see below)
readlink: no
follow_link: no
put_link: no
@ -96,7 +99,8 @@ tmpfile: no
Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
victim.
cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem.
cross-directory ->rename() and rename2() has (per-superblock)
->s_vfs_rename_sem.
See Documentation/filesystems/directory-locking for more detailed discussion
of the locking scheme for directory operations.

16
Documentation/filesystems/vfs.txt
View file

@ -347,6 +347,8 @@ struct inode_operations {
int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
int (*rename) (struct inode *, struct dentry *,
struct inode *, struct dentry *);
int (*rename2) (struct inode *, struct dentry *,
struct inode *, struct dentry *, unsigned int);
int (*readlink) (struct dentry *, char __user *,int);
void * (*follow_link) (struct dentry *, struct nameidata *);
void (*put_link) (struct dentry *, struct nameidata *, void *);
@ -414,6 +416,20 @@ otherwise noted.
rename: called by the rename(2) system call to rename the object to
have the parent and name given by the second inode and dentry.
rename2: this has an additional flags argument compared to rename.
If no flags are supported by the filesystem then this method
need not be implemented. If some flags are supported then the
filesystem must return -EINVAL for any unsupported or unknown
flags. Currently the following flags are implemented:
(1) RENAME_NOREPLACE: this flag indicates that if the target
of the rename exists the rename should fail with -EEXIST
instead of replacing the target. The VFS already checks for
existence, so for local filesystems the RENAME_NOREPLACE
implementation is equivalent to plain rename.
(2) RENAME_EXCHANGE: exchange source and target. Both must
exist; this is checked by the VFS. Unlike plain rename,
source and target may be of different type.
readlink: called by the readlink(2) system call. Only required if
you want to support reading symbolic links