diff options
author | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 01:49:20 -0500 |
---|---|---|
committer | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 01:50:17 -0500 |
commit | 5adcee1d8d32d7f305f6f5aaefdbf8f35adca177 (patch) | |
tree | 9292ebc9bb6a21b364a97a44d1b6857a565159c5 | |
parent | 3e880fb5e4bb6a012035e3edd0586ee2817c2e24 (diff) |
cgroup fs: avoid switching ->d_op on live dentry
Switching d_op on a live dentry is racy in general, so avoid it. In this case
it is a negative dentry, which is safer, but there are still concurrent ops
which may be called on d_op in that case (eg. d_revalidate). So in general
a filesystem may not do this. Fix cgroupfs so as not to do this.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
-rw-r--r-- | kernel/cgroup.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 66a416b42c18..163c890f436d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c | |||
@@ -763,6 +763,8 @@ EXPORT_SYMBOL_GPL(cgroup_unlock); | |||
763 | * -> cgroup_mkdir. | 763 | * -> cgroup_mkdir. |
764 | */ | 764 | */ |
765 | 765 | ||
766 | static struct dentry *cgroup_lookup(struct inode *dir, | ||
767 | struct dentry *dentry, struct nameidata *nd); | ||
766 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode); | 768 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode); |
767 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); | 769 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
768 | static int cgroup_populate_dir(struct cgroup *cgrp); | 770 | static int cgroup_populate_dir(struct cgroup *cgrp); |
@@ -2180,7 +2182,7 @@ static const struct file_operations cgroup_file_operations = { | |||
2180 | }; | 2182 | }; |
2181 | 2183 | ||
2182 | static const struct inode_operations cgroup_dir_inode_operations = { | 2184 | static const struct inode_operations cgroup_dir_inode_operations = { |
2183 | .lookup = simple_lookup, | 2185 | .lookup = cgroup_lookup, |
2184 | .mkdir = cgroup_mkdir, | 2186 | .mkdir = cgroup_mkdir, |
2185 | .rmdir = cgroup_rmdir, | 2187 | .rmdir = cgroup_rmdir, |
2186 | .rename = cgroup_rename, | 2188 | .rename = cgroup_rename, |
@@ -2196,13 +2198,29 @@ static inline struct cftype *__file_cft(struct file *file) | |||
2196 | return __d_cft(file->f_dentry); | 2198 | return __d_cft(file->f_dentry); |
2197 | } | 2199 | } |
2198 | 2200 | ||
2199 | static int cgroup_create_file(struct dentry *dentry, mode_t mode, | 2201 | static int cgroup_delete_dentry(struct dentry *dentry) |
2200 | struct super_block *sb) | 2202 | { |
2203 | return 1; | ||
2204 | } | ||
2205 | |||
2206 | static struct dentry *cgroup_lookup(struct inode *dir, | ||
2207 | struct dentry *dentry, struct nameidata *nd) | ||
2201 | { | 2208 | { |
2202 | static const struct dentry_operations cgroup_dops = { | 2209 | static const struct dentry_operations cgroup_dentry_operations = { |
2210 | .d_delete = cgroup_delete_dentry, | ||
2203 | .d_iput = cgroup_diput, | 2211 | .d_iput = cgroup_diput, |
2204 | }; | 2212 | }; |
2205 | 2213 | ||
2214 | if (dentry->d_name.len > NAME_MAX) | ||
2215 | return ERR_PTR(-ENAMETOOLONG); | ||
2216 | dentry->d_op = &cgroup_dentry_operations; | ||
2217 | d_add(dentry, NULL); | ||
2218 | return NULL; | ||
2219 | } | ||
2220 | |||
2221 | static int cgroup_create_file(struct dentry *dentry, mode_t mode, | ||
2222 | struct super_block *sb) | ||
2223 | { | ||
2206 | struct inode *inode; | 2224 | struct inode *inode; |
2207 | 2225 | ||
2208 | if (!dentry) | 2226 | if (!dentry) |
@@ -2228,7 +2246,6 @@ static int cgroup_create_file(struct dentry *dentry, mode_t mode, | |||
2228 | inode->i_size = 0; | 2246 | inode->i_size = 0; |
2229 | inode->i_fop = &cgroup_file_operations; | 2247 | inode->i_fop = &cgroup_file_operations; |
2230 | } | 2248 | } |
2231 | dentry->d_op = &cgroup_dops; | ||
2232 | d_instantiate(dentry, inode); | 2249 | d_instantiate(dentry, inode); |
2233 | dget(dentry); /* Extra count - pin the dentry in core */ | 2250 | dget(dentry); /* Extra count - pin the dentry in core */ |
2234 | return 0; | 2251 | return 0; |