[PATCH 04/20] sysfs: Handle the general case of removing of directories with subdirectories

Eric W. Biederman
2009-05-21T00:29:30Z

From: Eric W. Biederman <ebiederm@xmission.com>

Modify sysfs to properly remove directories containing attributes and
subdirectories. The code is relatively simple and means we don't have
to worry about what might use this logic.

In a quick survey I have only found /sys/dev/char and /sys/dev/block that are
removing non-enmpty directories today (and they are exclusively filled with symlinks).
So only removing empty directories does not appear to be an option.

I don't hold sysfs_mutex across the entire operation as that is unneeded
for coherence at the sysfs level and some level of coordination is expected
at the upper layers.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/sysfs/dir.c | 54 ++++++++++++++++++++++++++----------------------------
1 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index b95cc07..50702b3 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -732,43 +732,41 @@ const struct inode_operations sysfs_dir_inode_operations = {
.setattr = sysfs_setattr,
};

-static void remove_dir(struct sysfs_dirent *sd)
+static struct sysfs_dirent *sysfs_get_one(struct sysfs_dirent *dir_sd)
{
- struct sysfs_addrm_cxt acxt;
-
- sysfs_addrm_start(&acxt, sd->s_parent);
- sysfs_remove_one(&acxt, sd);
- sysfs_addrm_finish(&acxt);
-}
-
-void sysfs_remove_subdir(struct sysfs_dirent *sd)
-{
- remove_dir(sd);
+ struct sysfs_dirent *sd = dir_sd;
+ mutex_lock(&sysfs_mutex);
+ while ((sysfs_type(sd) == SYSFS_DIR) && sd->s_dir.children)
+ sd = sd->s_dir.children;
+ if (sd != dir_sd)
+ sysfs_get(sd);
+ else
+ sd = NULL;
+ mutex_unlock(&sysfs_mutex);
+ return sd;
}

-
-static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
+static void remove_dir(struct sysfs_dirent *dir_sd)
{
struct sysfs_addrm_cxt acxt;
- struct sysfs_dirent **pos;
-
- if (!dir_sd)
- return;
+ struct sysfs_dirent *sd;

pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
- sysfs_addrm_start(&acxt, dir_sd);
- pos = &dir_sd->s_dir.children;
- while (*pos) {
- struct sysfs_dirent *sd = *pos;

- if (sysfs_type(sd) != SYSFS_DIR)
- sysfs_remove_one(&acxt, sd);
- else
- pos = &(*pos)->s_sibling;
+ while ((sd = sysfs_get_one(dir_sd))) {
+ sysfs_addrm_start(&acxt, sd->s_parent);
+ sysfs_remove_one(&acxt, sd);
+ sysfs_addrm_finish(&acxt);
+ sysfs_put(sd);
}
+ sysfs_addrm_start(&acxt, dir_sd->s_parent);
+ sysfs_remove_one(&acxt, dir_sd);
sysfs_addrm_finish(&acxt);
+}

- remove_dir(dir_sd);
+void sysfs_remove_subdir(struct sysfs_dirent *sd)
+{
+ remove_dir(sd);
}

/**
@@ -788,7 +786,7 @@ void sysfs_remove_dir(struct kobject * kobj)
kobj->sd = NULL;
spin_unlock(&sysfs_assoc_lock);

- __sysfs_remove_dir(sd);
+ remove_dir(sd);
}

int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
--
1.6.1.2.350.g88cc