Cc: Li Zefan <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Lennart Poettering <[email protected]>
Signed-off-by: Aristeu Rozanski <[email protected]>
---
Documentation/filesystems/00-INDEX | 3 ++
Documentation/filesystems/simple_xattr.txt | 42 +++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)
Index: github/Documentation/filesystems/00-INDEX
===================================================================
--- github.orig/Documentation/filesystems/00-INDEX 2012-09-05
11:51:50.870969722 -0400
+++ github/Documentation/filesystems/00-INDEX 2012-09-05 12:10:46.250211947
-0400
@@ -96,6 +96,9 @@
- how to use the seq_file API
sharedsubtree.txt
- a description of shared subtrees for namespaces.
+simple_xattr.txt
+ - description of extended attributes for memory backed filesystems
+ like tmpfs and cgroup filesystem.
spufs.txt
- info and mount options for the SPU filesystem used on Cell.
sysfs-pci.txt
Index: github/Documentation/filesystems/simple_xattr.txt
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ github/Documentation/filesystems/simple_xattr.txt 2012-09-05
12:10:46.250211947 -0400
@@ -0,0 +1,42 @@
+Simple Extended Attributes for Memory Backed Filesystems Interface
+==================================================================
+
+Implements extended attributes storage using kernel memory. Users of these
+functions are strongly advised against allowing user or any other kind of
+extended attributes that can be manipulated by unprivileged users, since it'd
+be trivial to exhaust kernel memory.
+
+The filesystem implementation is responsible by storing a simple_xattrs
+structure for every directory and file and to implement setxattr() and
+getxattr() calls. Also, setxattr() should filter off by name the unsupported
+types.
+
+void simple_xattrs_init(struct simple_xattrs *xattrs)
+- Initializes a pre allocated structure
+
+void simple_xattrs_free(struct simple_xattrs *xattrs)
+- Frees up all the extended attributes and any resources allocated by
+ simple_xattrs_init
+
+struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
+- Allocates a extended attribute entry
+
+void simple_xattr_list_add(struct simple_xattrs *xattrs,
+ struct simple_xattr *new_xattr)
+int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
+- Adds and removes an extended attribute from the list
+
+int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
+ void *buffer, size_t size);
+- Returns the value of an extended attribute searching by name
+
+int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+ const void *value, size_t size, int flags);
+- Sets a new value for a given extended attribute. Specifying value as
+ NULL will remove the entry. If XATTR_CREATE is set in flags, no extended
+ attribute with the same name may exist. If XATTR_REPLACE is set, the
+ extended attribute has to exist or the operation will fail
+
+ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
+ size_t size);
+- Lists the existing extended attributes names in a given buffer
--
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