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| author | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:49:21 +1100 |
|---|---|---|
| committer | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:50:17 +1100 |
| commit | fbc8d4c04626e015b18cc61199f505920abb48f0 (patch) | |
| tree | 31cd59dd54966d225ae159f41308798b2d58b8a2 /fs/configfs | |
| parent | 5adcee1d8d32d7f305f6f5aaefdbf8f35adca177 (diff) | |
| download | lwn-fbc8d4c04626e015b18cc61199f505920abb48f0.tar.gz lwn-fbc8d4c04626e015b18cc61199f505920abb48f0.zip | |
config 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 configfs so as not to do this.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Diffstat (limited to 'fs/configfs')
| -rw-r--r-- | fs/configfs/dir.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 0b502f80c691..578706969415 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -232,10 +232,8 @@ int configfs_make_dirent(struct configfs_dirent * parent_sd, sd->s_mode = mode; sd->s_dentry = dentry; - if (dentry) { + if (dentry) dentry->d_fsdata = configfs_get(sd); - dentry->d_op = &configfs_dentry_ops; - } return 0; } @@ -278,7 +276,6 @@ static int create_dir(struct config_item * k, struct dentry * p, error = configfs_create(d, mode, init_dir); if (!error) { inc_nlink(p->d_inode); - (d)->d_op = &configfs_dentry_ops; } else { struct configfs_dirent *sd = d->d_fsdata; if (sd) { @@ -371,9 +368,7 @@ int configfs_create_link(struct configfs_symlink *sl, CONFIGFS_ITEM_LINK); if (!err) { err = configfs_create(dentry, mode, init_symlink); - if (!err) - dentry->d_op = &configfs_dentry_ops; - else { + if (err) { struct configfs_dirent *sd = dentry->d_fsdata; if (sd) { spin_lock(&configfs_dirent_lock); @@ -493,7 +488,11 @@ static struct dentry * configfs_lookup(struct inode *dir, * If it doesn't exist and it isn't a NOT_PINNED item, * it must be negative. */ - return simple_lookup(dir, dentry, nd); + if (dentry->d_name.len > NAME_MAX) + return ERR_PTR(-ENAMETOOLONG); + dentry->d_op = &configfs_dentry_ops; + d_add(dentry, NULL); + return NULL; } out: @@ -685,6 +684,7 @@ static int create_default_group(struct config_group *parent_group, ret = -ENOMEM; child = d_alloc(parent, &name); if (child) { + child->d_op = &configfs_dentry_ops; d_add(child, NULL); ret = configfs_attach_group(&parent_group->cg_item, @@ -1682,6 +1682,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) err = -ENOMEM; dentry = d_alloc(configfs_sb->s_root, &name); if (dentry) { + dentry->d_op = &configfs_dentry_ops; d_add(dentry, NULL); err = configfs_attach_group(sd->s_element, &group->cg_item, |