This patch implements sysfs name formatting. sysfs_add_link() is
passed @name_fmt instead of @fmt. In the format string only
"%[:alnum:]" and "%%" are handled specially. "%0" is substitued with
the name of @target, "%3" with the name of the third ancestor of
@target, "%[aA]" the 10th and "%[zZ]" with 35th. "%%" is substituted
with "%".
This formatting is mainly to make symlink renaming automatic such that
when the target or one of its ancestors gets renamed the symlink can
be renamed together automatically & atomically. It also simplifies
sysfs creation a bit by allowing callers to use static format string
instead of formatting symlink name itself.
@name to kobject based sysfs_create_link() is not interpreted as
format string to keep backward compatibility.
Signed-off-by: Tejun Heo <[EMAIL PROTECTED]>
---
fs/sysfs/dir.c | 3 +
fs/sysfs/kobject.c | 2 +-
fs/sysfs/symlink.c | 245 ++++++++++++++++++++++++++++++++++++++++++++++--
fs/sysfs/sysfs.h | 9 ++
include/linux/sysfs.h | 6 +-
5 files changed, 250 insertions(+), 15 deletions(-)
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index d50d3ac..b042a2e 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -295,6 +295,9 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
sysfs_put(sd->s_link.target);
if (sd->s_flags & SYSFS_FLAG_NAME_COPIED)
kfree(sd->s_name);
+ if (sd->s_flags & SYSFS_FLAG_LINK_NAME_FMT_COPIED)
+ kfree(sd->s_link.name_fmt);
+
kfree(sd->s_iattr);
sysfs_free_ino(sd->s_ino);
kmem_cache_free(sysfs_dir_cachep, sd);
diff --git a/fs/sysfs/kobject.c b/fs/sysfs/kobject.c
index 16e10de..7ea9186 100644
--- a/fs/sysfs/kobject.c
+++ b/fs/sysfs/kobject.c
@@ -425,7 +425,7 @@ int sysfs_create_link(struct kobject *kobj, struct kobject
*target,
if (!target_sd)
return -ENOENT;
- sd = sysfs_add_link(parent_sd, name, SYSFS_COPY_NAME, target_sd);
+ sd = __sysfs_add_link(parent_sd, name, SYSFS_COPY_NAME, target_sd, 0);
sysfs_put(target_sd);
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 42ecb69..296fef5 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -7,6 +7,7 @@
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/mutex.h>
+#include <linux/ctype.h>
#include "sysfs.h"
@@ -43,16 +44,162 @@ static void fill_object_path(struct sysfs_dirent *sd, char
*buffer, int length)
}
}
+size_t sysfs_format_link_name(const char *fmt, struct sysfs_dirent *target,
+ char *buf, struct sysfs_dirent *renamed_sd,
+ struct sysfs_dirent *new_parent,
+ const char *new_name)
+{
+ char *dst = buf;
+ int cnt = 0;
+
+ while (*fmt != '\0') {
+ char ch = *fmt++, next = *fmt;
+ struct sysfs_dirent *tsd;
+ const char *tname;
+ int level;
+ size_t len;
+
+ if (ch != '%' || !isalnum(next)) {
+ if (dst)
+ *dst++ = ch;
+ cnt++;
+ /* %% is % */
+ if (ch== '%' && next == '%')
+ fmt++;
+ continue;
+ }
+
+ /* Seen %[:alnum:]. %0 is the target's name. %z is
+ * the name of the 35th ancestor of the target.
+ */
+ fmt++;
+ if (isdigit(next))
+ level = next - '0';
+ else
+ level = tolower(next) - 'a' + 10;
+
+ /* Work up level times and use its name. It's a bit
+ * complicated due to the renamed node handling.
+ */
+ tsd = target;
+ while (level && tsd->s_parent) {
+ if (tsd == renamed_sd)
+ tsd = new_parent;
+ else
+ tsd = tsd->s_parent;
+ level--;
+ }
+ WARN_ON(level);
+
+ tname = tsd->s_name;
+ if (tsd == renamed_sd)
+ tname = new_name;
+
+ /* got the name, copy it */
+ len = strlen(tname);
+ if (dst) {
+ memcpy(dst, tname, len);
+ dst += len;
+ }
+ cnt += len;
+ }
+
+ if (dst)
+ *dst = '\0';
+ return cnt;
+}
+
/**
- * sysfs_add_link - add a new sysfs symlink
+ * sysfs_link_name - format the name of symlink
+ * @fmt: format string
+ * @target: target sysfs_dirent the symlink points to
+ * @link_name: out parameter for the formatted string
+ * @renamed_sd: renamed sysfs_dirent (can be NULL)
+ * @new_parent: new parent of @renamed_sd (NULL if [EMAIL PROTECTED])
+ * @new_name: new name of @renamed_sd (NULL if [EMAIL PROTECTED])
+ *
+ * Format the name of the symlink according to @fmt and given
+ * parameters.
+ *
+ * %[:alnum:] has special meaning in the format string. %0 is
+ * substituted with the target's name. %1 is the parent, %2 the
+ * parent's parent, %9 the 9th ancestor, %a or %A the 10th
+ * ancestor and so on upto %z or %Z which is substitued with the
+ * name of the 35th ancestor. %% is substituted with %. All
+ * other sequences are copied verbatim.
+ *
+ * @renamed_sd is used to override the specified sd's parent and
+ * name. If a sd which matches @renamed_sd is in the path
+ * between sysfs_root and @sd, @new_parent is used instead of
+ * sd->s_parent and @new_name is used instead of sd->s_name.
+ * This is used to format new symlink name while preparing to
+ * rename the target or one of the ancestors of it.
+ *
+ * LOCKING:
+ * mutex_lock(sysfs_op_mutex)
+ *
+ * RETURNS:
+ * 1 if success and the buffer [EMAIL PROTECTED] points to needs to be
+ * freed later. 0 if success and [EMAIL PROTECTED] points to @fmt
+ * directly. -errno on failure.
+ */
+int sysfs_link_name(const char *fmt, struct sysfs_dirent *target,
+ const char **link_name, struct sysfs_dirent *renamed_sd,
+ struct sysfs_dirent *new_parent, const char *new_name)
+{
+ size_t len;
+ char *buf;
+
+ /* nothing to format? */
+ if (!strchr(fmt, '%')) {
+ *link_name = fmt;
+ return 0;
+ }
+
+ /* determine length and allocate space for the formatted string */
+ len = sysfs_format_link_name(fmt, target, NULL,
+ renamed_sd, new_parent, new_name);
+ buf = kmalloc(len + 1, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ /* format it */
+ sysfs_format_link_name(fmt, target, buf,
+ renamed_sd, new_parent, new_name);
+ *link_name = buf;
+ return 1;
+}
+
+/**
+ * __sysfs_add_link - add a new sysfs symlink
* @parent: sysfs_dirent to add symlink under
- * @name: name of the symlink
+ * @name_fmt: format string for the name of the symlink
* @mode: SYSFS_* flags for the new symlink
* @target: target of the symlink
+ * @format: whether format symlink name or not
*
* Add a new symlink which points to @target under @parent with
* the specified parameters.
*
+ * If @format is not zero, @name_fmt is interpreted as format
+ * string and the symlink name will be formatted accordingly.
+ * Also, the symlink will be chained into the links list of the
+ * @target and will be renamed automatically when the @target is
+ * renamed or moved.
+ *
+ * If @format is zero, @name_fmt is taken as verbatim name of the
+ * symlink and won't be renamed automatically no matter what
+ * happens to the @target.
+ *
+ * SYSFS_COPY_NAME always specifies that the string @name_fmt
+ * points to should be copied whether it's interpreted as format
+ * string or not.
+ *
+ * This is an internal function to be used to implement
+ * sysfs_add_link() and sysfs_create_link(). @format is
+ * necessary to support the original sysfs_create_link()
+ * semantics where the symlink name is specified verbatim.
+ *
* LOCKING:
* Kernel thread context (may sleep).
*
@@ -60,27 +207,103 @@ static void fill_object_path(struct sysfs_dirent *sd,
char *buffer, int length)
* Pointer to the new sysfs_dirent on success, ERR_PTR() value on
* error.
*/
-struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
- const char *name, mode_t mode,
- struct sysfs_dirent *target)
+struct sysfs_dirent *__sysfs_add_link(struct sysfs_dirent *parent,
+ const char *name_fmt, mode_t mode,
+ struct sysfs_dirent *target, int format)
{
- struct sysfs_dirent *sd;
+ struct sysfs_dirent *sd = NULL;
+ unsigned int flags = 0;
+ const char *name;
+ struct sysfs_addrm_cxt acxt;
+ int rc;
+
+ /* acquire locks early for link name formatting */
+ sysfs_addrm_start(&acxt);
/* Only symlink to directories are allowed. This is an
- * artificial limitation. If ever needed, allowing symlinks
- * to point to other types of sysfs nodes isn't difficult.
+ * artificial limitation mainly to reduce the size of
+ * sysfs_dirent by putting the links head into s_dir union
+ * member. If ever needed, allowing symlinks to point to
+ * other types of sysfs nodes isn't difficult.
*/
+ rc = -EINVAL;
if (sysfs_type(target) != SYSFS_DIR)
- return ERR_PTR(-EINVAL);
+ goto err;
+
+ if (format) {
+ /* SYSFS_COPY_NAME means 'copy the format string' */
+ rc = -ENOMEM;
+ if (mode & SYSFS_COPY_NAME) {
+ name_fmt = kstrdup(name_fmt, GFP_KERNEL);
+ if (!name_fmt)
+ goto err;
+ mode &= ~SYSFS_COPY_NAME;
+ flags |= SYSFS_FLAG_LINK_NAME_FMT_COPIED;
+ }
+
+ /* format name */
+ rc = sysfs_link_name(name_fmt, target, &name, NULL, NULL, NULL);
+ if (rc < 0)
+ goto err;
+ /* set NAME_COPIED if name has been allocated and formatted */
+ if (rc)
+ flags |= SYSFS_FLAG_NAME_COPIED;
+ } else
+ name = name_fmt;
/* allocate & initialize */
+ rc = -ENOMEM;
sd = sysfs_new_dirent(name, mode | S_IRWXUGO, SYSFS_LINK);
if (!sd)
- return ERR_PTR(-ENOMEM);
+ goto err;
+ sd->s_flags |= flags;
+ sd->s_link.name_fmt = name_fmt;
sd->s_link.target = sysfs_get(target);
- return sysfs_insert_one(parent, sd);
+ /* add the new node */
+ rc = sysfs_add_one(&acxt, parent, sd);
+ if (rc) {
+ sysfs_put(sd); /* target is put when sd is released */
+ goto err;
+ }
+
+ sysfs_addrm_finish(&acxt);
+ return sd;
+
+ err:
+ sysfs_addrm_finish(&acxt);
+ if (flags & SYSFS_FLAG_LINK_NAME_FMT_COPIED)
+ kfree(name_fmt);
+ if (flags & SYSFS_FLAG_NAME_COPIED)
+ kfree(name);
+ return ERR_PTR(rc);
+}
+
+/**
+ * sysfs_add_link - add a new sysfs symlink
+ * @parent: sysfs_dirent to add symlink under
+ * @name_fmt: format string for the name of the symlink
+ * @mode: SYSFS_* flags for the new symlink
+ * @target: target of the symlink
+ *
+ * Add a new symlink which points to @target under @parent with
+ * the specified parameters. @name_fmt is always interpreted as
+ * format string for symlink name. See __sysfs_add_link() for
+ * details.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ *
+ * RETURNS:
+ * Pointer to the new sysfs_dirent on success, ERR_PTR() value on
+ * error.
+ */
+struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
+ const char *name, mode_t mode,
+ struct sysfs_dirent *target)
+{
+ return __sysfs_add_link(parent, name, mode, target, 1);
}
EXPORT_SYMBOL_GPL(sysfs_add_link);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 732b292..9167032 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -9,6 +9,7 @@ struct sysfs_elem_dir {
struct sysfs_elem_link {
struct sysfs_dirent *target;
+ const char *name_fmt;
};
struct sysfs_elem_file {
@@ -62,6 +63,7 @@ struct sysfs_dirent {
#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
#define SYSFS_FLAG_REMOVED 0x0200
#define SYSFS_FLAG_NAME_COPIED 0x0400
+#define SYSFS_FLAG_LINK_NAME_FMT_COPIED 0x0800
static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
{
@@ -152,4 +154,11 @@ extern const struct file_operations
sysfs_bin_file_operations;
/*
* symlink.c
*/
+struct sysfs_dirent *__sysfs_add_link(struct sysfs_dirent *parent,
+ const char *name, mode_t mode,
+ struct sysfs_dirent *target, int format);
+int sysfs_link_name(const char *fmt, struct sysfs_dirent *target,
+ const char **link_name, struct sysfs_dirent *renamed_sd,
+ struct sysfs_dirent *new_parent, const char *new_name);
+
extern const struct inode_operations sysfs_link_inode_operations;
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index f0279a7..5afe3bd 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -29,7 +29,7 @@ struct vm_area_struct;
* specific flags.
*/
#define SYSFS_DIR_MODE (S_IRWXU | S_IRUGO | S_IXUGO)
-#define SYSFS_COPY_NAME 010000 /* copy passed @name */
+#define SYSFS_COPY_NAME 010000 /* copy passed @name[_fmt] */
/* collection of all flags for verification */
#define SYSFS_MODE_FLAGS SYSFS_COPY_NAME
@@ -61,7 +61,7 @@ struct sysfs_dirent *sysfs_add_bin(struct sysfs_dirent
*parent,
const char *name, mode_t mode, size_t size,
const struct sysfs_bin_ops *bops, void *data);
struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
- const char *name, mode_t mode,
+ const char *name_fmt, mode_t mode,
struct sysfs_dirent *target);
struct sysfs_dirent *sysfs_find_child(struct sysfs_dirent *parent,
@@ -100,7 +100,7 @@ static inline struct sysfs_dirent *sysfs_add_bin(struct
sysfs_dirent *parent,
}
static inline struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
- const char *name, mode_t mode,
+ const char *name_fmt, mode_t mode,
struct sysfs_dirent *target)
{
return NULL;
--
1.5.0.3
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
