From: "J. Bruce Fields" <bfields@xxxxxxxxxx> To rely on the i_mutex for exclusion between setlease and rename, we need rename to take the i_mutex on the source as well as on any possible target. Also fix up lockdep and the Documentation/filesystems/directory-locking documentation. Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> --- Documentation/filesystems/directory-locking | 11 ++++++----- fs/namei.c | 12 ++++++++++++ include/linux/fs.h | 9 ++++++--- 3 files changed, 24 insertions(+), 8 deletions(-) diff --git a/Documentation/filesystems/directory-locking b/Documentation/filesystems/directory-locking index ff7b611..9edbcd2 100644 --- a/Documentation/filesystems/directory-locking +++ b/Documentation/filesystems/directory-locking @@ -12,8 +12,8 @@ kinds of locks - per-inode (->i_mutex) and per-filesystem locks victim and calls the method. 4) rename() that is _not_ cross-directory. Locking rules: caller locks -the parent, finds source and target, if target already exists - locks it -and then calls the method. +the parent, finds source and target, locks source, also locks target if +it already exists, and then calls the method. 5) link creation. Locking rules: * lock parent @@ -30,6 +30,7 @@ rules: fail with -ENOTEMPTY * if new parent is equal to or is a descendent of source fail with -ELOOP + * lock source if it is not a directory. * if target exists - lock it. * call the method. @@ -56,9 +57,9 @@ objects - A < B iff A is an ancestor of B. renames will be blocked on filesystem lock and we don't start changing the order until we had acquired all locks). -(3) any operation holds at most one lock on non-directory object and - that lock is acquired after all other locks. (Proof: see descriptions - of operations). +(3) locks on non-directory objects are acquired only after taking locks + on their parents (which remain their parents until all locks are + acquired, by (1) and (2)). (Proof: see descriptions of operations). Now consider the minimal deadlock. Each process is blocked on attempt to acquire some lock and already holds at least one lock. Let's diff --git a/fs/namei.c b/fs/namei.c index 4516958..1e0c383 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3076,6 +3076,7 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { struct inode *target = new_dentry->d_inode; + struct inode *source = old_dentry->d_inode; int error; error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); @@ -3083,6 +3084,7 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, return error; dget(new_dentry); + mutex_lock_nested(&source->i_mutex, I_MUTEX_RENAME_SOURCE); if (target) mutex_lock(&target->i_mutex); @@ -3090,6 +3092,14 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) goto out; + error = break_lease(source, BREAK_ONLY_DELEGS|BREAK_R_AND_W_LEASES); + if (error) + goto out; + if (target) { + error = break_lease(target, BREAK_ONLY_DELEGS|BREAK_R_AND_W_LEASES); + if (error) + goto out; + } error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); if (error) goto out; @@ -3101,6 +3111,8 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, out: if (target) mutex_unlock(&target->i_mutex); +out_unlock_source: + mutex_unlock(&source->i_mutex); dput(new_dentry); return error; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 89c8481..f6a09b4 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -855,10 +855,12 @@ static inline int inode_unhashed(struct inode *inode) * 0: the object of the current VFS operation * 1: parent * 2: child/target - * 3: quota file + * 3: xattr + * 4: quota file + * 5: the file being renamed (used only in rename of a non-directory) * * The locking order between these classes is - * parent -> child -> normal -> xattr -> quota + * parent -> child -> rename_source -> normal -> xattr -> quota */ enum inode_i_mutex_lock_class { @@ -866,7 +868,8 @@ enum inode_i_mutex_lock_class I_MUTEX_PARENT, I_MUTEX_CHILD, I_MUTEX_XATTR, - I_MUTEX_QUOTA + I_MUTEX_QUOTA, + I_MUTEX_RENAME_SOURCE }; /* -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html