Cc: Li Zefan Cc: Tejun Heo Cc: Hugh Dickins Cc: Hillf Danton Cc: Lennart Poettering Signed-off-by: Aristeu Rozanski --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/