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-rw-r--r--Documentation/filesystems/Locking2
-rw-r--r--Documentation/filesystems/vfs.txt23
2 files changed, 24 insertions, 1 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 28bfea75bcf2..59c14159cc47 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -15,6 +15,7 @@ prototypes:
15 int (*d_delete)(struct dentry *); 15 int (*d_delete)(struct dentry *);
16 void (*d_release)(struct dentry *); 16 void (*d_release)(struct dentry *);
17 void (*d_iput)(struct dentry *, struct inode *); 17 void (*d_iput)(struct dentry *, struct inode *);
18 char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
18 19
19locking rules: 20locking rules:
20 none have BKL 21 none have BKL
@@ -25,6 +26,7 @@ d_compare: no yes no no
25d_delete: yes no yes no 26d_delete: yes no yes no
26d_release: no no no yes 27d_release: no no no yes
27d_iput: no no no yes 28d_iput: no no no yes
29d_dname: no no no no
28 30
29--------------------------- inode_operations --------------------------- 31--------------------------- inode_operations ---------------------------
30prototypes: 32prototypes:
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index ea271f2d3954..a47cc819f37b 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -827,7 +827,7 @@ This describes how a filesystem can overload the standard dentry
827operations. Dentries and the dcache are the domain of the VFS and the 827operations. Dentries and the dcache are the domain of the VFS and the
828individual filesystem implementations. Device drivers have no business 828individual filesystem implementations. Device drivers have no business
829here. These methods may be set to NULL, as they are either optional or 829here. These methods may be set to NULL, as they are either optional or
830the VFS uses a default. As of kernel 2.6.13, the following members are 830the VFS uses a default. As of kernel 2.6.22, the following members are
831defined: 831defined:
832 832
833struct dentry_operations { 833struct dentry_operations {
@@ -837,6 +837,7 @@ struct dentry_operations {
837 int (*d_delete)(struct dentry *); 837 int (*d_delete)(struct dentry *);
838 void (*d_release)(struct dentry *); 838 void (*d_release)(struct dentry *);
839 void (*d_iput)(struct dentry *, struct inode *); 839 void (*d_iput)(struct dentry *, struct inode *);
840 char *(*d_dname)(struct dentry *, char *, int);
840}; 841};
841 842
842 d_revalidate: called when the VFS needs to revalidate a dentry. This 843 d_revalidate: called when the VFS needs to revalidate a dentry. This
@@ -859,6 +860,26 @@ struct dentry_operations {
859 VFS calls iput(). If you define this method, you must call 860 VFS calls iput(). If you define this method, you must call
860 iput() yourself 861 iput() yourself
861 862
863 d_dname: called when the pathname of a dentry should be generated.
864 Usefull for some pseudo filesystems (sockfs, pipefs, ...) to delay
865 pathname generation. (Instead of doing it when dentry is created,
866 its done only when the path is needed.). Real filesystems probably
867 dont want to use it, because their dentries are present in global
868 dcache hash, so their hash should be an invariant. As no lock is
869 held, d_dname() should not try to modify the dentry itself, unless
870 appropriate SMP safety is used. CAUTION : d_path() logic is quite
871 tricky. The correct way to return for example "Hello" is to put it
872 at the end of the buffer, and returns a pointer to the first char.
873 dynamic_dname() helper function is provided to take care of this.
874
875Example :
876
877static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen)
878{
879 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
880 dentry->d_inode->i_ino);
881}
882
862Each dentry has a pointer to its parent dentry, as well as a hash list 883Each dentry has a pointer to its parent dentry, as well as a hash list
863of child dentries. Child dentries are basically like files in a 884of child dentries. Child dentries are basically like files in a
864directory. 885directory.