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authorTejun Heo <tj@kernel.org>2013-11-28 23:54:35 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-30 06:08:39 +0400
commit2072f1afddfe9fa00c1c0c79f8986707324ec65b (patch)
tree636f5f2e0c44082afcded77328bcbcdb62b58f51 /fs/kernfs
parent414985ae23c031efbd6d16d484dea8b5de28b8f7 (diff)
downloadlinux-2072f1afddfe9fa00c1c0c79f8986707324ec65b.tar.xz
sysfs, kernfs: move symlink core code to fs/kernfs/symlink.c
Move core symlink code to fs/kernfs/symlink.c. fs/sysfs/symlink.c now only contains sysfs wrappers around kernfs interfaces. The respective declarations in fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h. This is pure relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
-rw-r--r--fs/kernfs/kernfs-internal.h5
-rw-r--r--fs/kernfs/symlink.c139
2 files changed, 144 insertions, 0 deletions
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 38e3a163e5ad..62ae35f997f7 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -149,4 +149,9 @@ extern const struct file_operations kernfs_file_operations;
void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
+/*
+ * symlink.c
+ */
+extern const struct inode_operations sysfs_symlink_inode_operations;
+
#endif /* __KERNFS_INTERNAL_H */
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 2578715baf0e..af3570bb4303 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -7,3 +7,142 @@
*
* This file is released under the GPLv2.
*/
+
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/namei.h>
+
+#include "kernfs-internal.h"
+
+/**
+ * kernfs_create_link - create a symlink
+ * @parent: directory to create the symlink in
+ * @name: name of the symlink
+ * @target: target node for the symlink to point to
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
+ const char *name,
+ struct sysfs_dirent *target)
+{
+ struct sysfs_dirent *sd;
+ struct sysfs_addrm_cxt acxt;
+ int error;
+
+ sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+ if (!sd)
+ return ERR_PTR(-ENOMEM);
+
+ if (parent->s_flags & SYSFS_FLAG_NS)
+ sd->s_ns = target->s_ns;
+ sd->s_symlink.target_sd = target;
+ kernfs_get(target); /* ref owned by symlink */
+
+ sysfs_addrm_start(&acxt);
+ error = sysfs_add_one(&acxt, sd, parent);
+ sysfs_addrm_finish(&acxt);
+
+ if (!error)
+ return sd;
+
+ kernfs_put(sd);
+ return ERR_PTR(error);
+}
+
+static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
+ struct sysfs_dirent *target_sd, char *path)
+{
+ struct sysfs_dirent *base, *sd;
+ char *s = path;
+ int len = 0;
+
+ /* go up to the root, stop at the base */
+ base = parent_sd;
+ while (base->s_parent) {
+ sd = target_sd->s_parent;
+ while (sd->s_parent && base != sd)
+ sd = sd->s_parent;
+
+ if (base == sd)
+ break;
+
+ strcpy(s, "../");
+ s += 3;
+ base = base->s_parent;
+ }
+
+ /* determine end of target string for reverse fillup */
+ sd = target_sd;
+ while (sd->s_parent && sd != base) {
+ len += strlen(sd->s_name) + 1;
+ sd = sd->s_parent;
+ }
+
+ /* check limits */
+ if (len < 2)
+ return -EINVAL;
+ len--;
+ if ((s - path) + len > PATH_MAX)
+ return -ENAMETOOLONG;
+
+ /* reverse fillup of target string from target to base */
+ sd = target_sd;
+ while (sd->s_parent && sd != base) {
+ int slen = strlen(sd->s_name);
+
+ len -= slen;
+ strncpy(s + len, sd->s_name, slen);
+ if (len)
+ s[--len] = '/';
+
+ sd = sd->s_parent;
+ }
+
+ return 0;
+}
+
+static int sysfs_getlink(struct dentry *dentry, char *path)
+{
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ struct sysfs_dirent *parent_sd = sd->s_parent;
+ struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
+ int error;
+
+ mutex_lock(&sysfs_mutex);
+ error = sysfs_get_target_path(parent_sd, target_sd, path);
+ mutex_unlock(&sysfs_mutex);
+
+ return error;
+}
+
+static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ int error = -ENOMEM;
+ unsigned long page = get_zeroed_page(GFP_KERNEL);
+ if (page) {
+ error = sysfs_getlink(dentry, (char *) page);
+ if (error < 0)
+ free_page((unsigned long)page);
+ }
+ nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
+ return NULL;
+}
+
+static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
+ void *cookie)
+{
+ char *page = nd_get_link(nd);
+ if (!IS_ERR(page))
+ free_page((unsigned long)page);
+}
+
+const struct inode_operations sysfs_symlink_inode_operations = {
+ .setxattr = sysfs_setxattr,
+ .readlink = generic_readlink,
+ .follow_link = sysfs_follow_link,
+ .put_link = sysfs_put_link,
+ .setattr = sysfs_setattr,
+ .getattr = sysfs_getattr,
+ .permission = sysfs_permission,
+};