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| author | Louis Rilling <louis.rilling@kerlabs.com> | 2008-06-20 14:09:22 +0200 |
|---|---|---|
| committer | Mark Fasheh <mfasheh@suse.com> | 2008-08-01 01:21:13 +0200 |
| commit | 9a73d78cda750f12e25eb811878f2d9dbab1bc6e (patch) | |
| tree | abdc6537d51ee4faeb41c452428f2bde72abc9c8 /fs/configfs/symlink.c | |
| parent | [PATCH] configfs: Fix symlink() to a removing item (diff) | |
| download | linux-9a73d78cda750f12e25eb811878f2d9dbab1bc6e.tar.xz linux-9a73d78cda750f12e25eb811878f2d9dbab1bc6e.zip | |
[PATCH] configfs: Fix failing symlink() making rmdir() fail
On a similar pattern as mkdir() vs rmdir(), a failing symlink() may make rmdir()
fail for the symlink's parent and the symlink's target as well.
failing symlink() making target's rmdir() fail:
process 1: process 2:
symlink("A/S" -> "B")
allow_link()
create_link()
attach to "B" links list
rmdir("B")
detach_prep("B")
error because of new link
configfs_create_link("A", "S")
error (eg -ENOMEM)
failing symlink() making parent's rmdir() fail:
process 1: process 2:
symlink("A/D/S" -> "B")
allow_link()
create_link()
attach to "B" links list
configfs_create_link("A/D", "S")
make_dirent("A/D", "S")
rmdir("A")
detach_prep("A")
detach_prep("A/D")
error because of "S"
create("S")
error (eg -ENOMEM)
We cannot use the same solution as for mkdir() vs rmdir(), since rmdir() on the
target cannot wait on the i_mutex of the new symlink's parent without risking a
deadlock (with other symlink() or sys_rename()). Instead we define a global
mutex protecting all configfs symlinks attachment, so that rmdir() can avoid the
races above.
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Diffstat (limited to 'fs/configfs/symlink.c')
| -rw-r--r-- | fs/configfs/symlink.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c index c12801a12c34..61a886dbd601 100644 --- a/fs/configfs/symlink.c +++ b/fs/configfs/symlink.c @@ -31,6 +31,9 @@ #include <linux/configfs.h> #include "configfs_internal.h" +/* Protects attachments of new symlinks */ +DEFINE_MUTEX(configfs_symlink_mutex); + static int item_depth(struct config_item * item) { struct config_item * p = item; @@ -147,7 +150,9 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna ret = type->ct_item_ops->allow_link(parent_item, target_item); if (!ret) { + mutex_lock(&configfs_symlink_mutex); ret = create_link(parent_item, target_item, dentry); + mutex_unlock(&configfs_symlink_mutex); if (ret && type->ct_item_ops->drop_link) type->ct_item_ops->drop_link(parent_item, target_item); |