UBIFS: simplify locking
This patch simplifies lock_[23]_inodes functions. We do not have to care about locking order, because UBIFS does this for @i_mutex and this is enough. Thanks to Al Viro for suggesting this. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
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Родитель
7078202e55
Коммит
82c1593cad
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@ -482,30 +482,29 @@ static int ubifs_dir_release(struct inode *dir, struct file *file)
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}
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/**
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* lock_2_inodes - lock two UBIFS inodes.
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* lock_2_inodes - a wrapper for locking two UBIFS inodes.
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* @inode1: first inode
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* @inode2: second inode
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*
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* We do not implement any tricks to guarantee strict lock ordering, because
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* VFS has already done it for us on the @i_mutex. So this is just a simple
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* wrapper function.
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*/
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static void lock_2_inodes(struct inode *inode1, struct inode *inode2)
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{
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if (inode1->i_ino < inode2->i_ino) {
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mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_2);
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mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_3);
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} else {
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mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
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mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_3);
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}
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mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
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mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
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}
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/**
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* unlock_2_inodes - unlock two UBIFS inodes inodes.
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* unlock_2_inodes - a wrapper for unlocking two UBIFS inodes.
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* @inode1: first inode
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* @inode2: second inode
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*/
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static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
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{
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mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
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mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
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mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
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}
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static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
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@ -527,6 +526,8 @@ static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
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dbg_gen("dent '%.*s' to ino %lu (nlink %d) in dir ino %lu",
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dentry->d_name.len, dentry->d_name.name, inode->i_ino,
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inode->i_nlink, dir->i_ino);
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ubifs_assert(mutex_is_locked(&dir->i_mutex));
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ubifs_assert(mutex_is_locked(&inode->i_mutex));
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err = dbg_check_synced_i_size(inode);
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if (err)
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return err;
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@ -580,6 +581,8 @@ static int ubifs_unlink(struct inode *dir, struct dentry *dentry)
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dbg_gen("dent '%.*s' from ino %lu (nlink %d) in dir ino %lu",
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dentry->d_name.len, dentry->d_name.name, inode->i_ino,
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inode->i_nlink, dir->i_ino);
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ubifs_assert(mutex_is_locked(&dir->i_mutex));
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ubifs_assert(mutex_is_locked(&inode->i_mutex));
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err = dbg_check_synced_i_size(inode);
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if (err)
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return err;
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@ -667,7 +670,8 @@ static int ubifs_rmdir(struct inode *dir, struct dentry *dentry)
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dbg_gen("directory '%.*s', ino %lu in dir ino %lu", dentry->d_name.len,
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dentry->d_name.name, inode->i_ino, dir->i_ino);
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ubifs_assert(mutex_is_locked(&dir->i_mutex));
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ubifs_assert(mutex_is_locked(&inode->i_mutex));
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err = check_dir_empty(c, dentry->d_inode);
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if (err)
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return err;
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@ -922,59 +926,30 @@ out_budg:
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}
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/**
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* lock_3_inodes - lock three UBIFS inodes for rename.
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* lock_3_inodes - a wrapper for locking three UBIFS inodes.
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* @inode1: first inode
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* @inode2: second inode
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* @inode3: third inode
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*
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* For 'ubifs_rename()', @inode1 may be the same as @inode2 whereas @inode3 may
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* be null.
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* This function is used for 'ubifs_rename()' and @inode1 may be the same as
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* @inode2 whereas @inode3 may be %NULL.
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*
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* We do not implement any tricks to guarantee strict lock ordering, because
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* VFS has already done it for us on the @i_mutex. So this is just a simple
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* wrapper function.
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*/
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static void lock_3_inodes(struct inode *inode1, struct inode *inode2,
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struct inode *inode3)
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{
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struct inode *i1, *i2, *i3;
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if (!inode3) {
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if (inode1 != inode2) {
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lock_2_inodes(inode1, inode2);
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return;
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}
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mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
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return;
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}
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if (inode1 == inode2) {
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lock_2_inodes(inode1, inode3);
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return;
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}
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/* 3 different inodes */
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if (inode1 < inode2) {
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i3 = inode2;
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if (inode1 < inode3) {
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i1 = inode1;
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i2 = inode3;
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} else {
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i1 = inode3;
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i2 = inode1;
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}
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} else {
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i3 = inode1;
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if (inode2 < inode3) {
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i1 = inode2;
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i2 = inode3;
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} else {
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i1 = inode3;
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i2 = inode2;
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}
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}
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mutex_lock_nested(&ubifs_inode(i1)->ui_mutex, WB_MUTEX_1);
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lock_2_inodes(i2, i3);
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mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
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if (inode2 != inode1)
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mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
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if (inode3)
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mutex_lock_nested(&ubifs_inode(inode3)->ui_mutex, WB_MUTEX_3);
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}
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/**
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* unlock_3_inodes - unlock three UBIFS inodes for rename.
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* unlock_3_inodes - a wrapper for unlocking three UBIFS inodes for rename.
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* @inode1: first inode
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* @inode2: second inode
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* @inode3: third inode
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@ -982,11 +957,11 @@ static void lock_3_inodes(struct inode *inode1, struct inode *inode2,
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static void unlock_3_inodes(struct inode *inode1, struct inode *inode2,
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struct inode *inode3)
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{
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mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
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if (inode1 != inode2)
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mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
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if (inode3)
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mutex_unlock(&ubifs_inode(inode3)->ui_mutex);
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if (inode1 != inode2)
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mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
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mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
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}
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static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry,
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@ -1020,6 +995,11 @@ static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry,
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"dir ino %lu", old_dentry->d_name.len, old_dentry->d_name.name,
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old_inode->i_ino, old_dir->i_ino, new_dentry->d_name.len,
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new_dentry->d_name.name, new_dir->i_ino);
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ubifs_assert(mutex_is_locked(&old_dir->i_mutex));
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ubifs_assert(mutex_is_locked(&new_dir->i_mutex));
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if (unlink)
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ubifs_assert(mutex_is_locked(&new_inode->i_mutex));
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if (unlink && is_dir) {
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err = check_dir_empty(c, new_inode);
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