From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/reiserfs/lock.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) create mode 100644 fs/reiserfs/lock.c (limited to 'fs/reiserfs/lock.c') diff --git a/fs/reiserfs/lock.c b/fs/reiserfs/lock.c new file mode 100644 index 000000000..46bd7bd63 --- /dev/null +++ b/fs/reiserfs/lock.c @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "reiserfs.h" +#include + +/* + * The previous reiserfs locking scheme was heavily based on + * the tricky properties of the Bkl: + * + * - it was acquired recursively by a same task + * - the performances relied on the release-while-schedule() property + * + * Now that we replace it by a mutex, we still want to keep the same + * recursive property to avoid big changes in the code structure. + * We use our own lock_owner here because the owner field on a mutex + * is only available in SMP or mutex debugging, also we only need this field + * for this mutex, no need for a system wide mutex facility. + * + * Also this lock is often released before a call that could block because + * reiserfs performances were partially based on the release while schedule() + * property of the Bkl. + */ +void reiserfs_write_lock(struct super_block *s) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + + if (sb_i->lock_owner != current) { + mutex_lock(&sb_i->lock); + sb_i->lock_owner = current; + } + + /* No need to protect it, only the current task touches it */ + sb_i->lock_depth++; +} + +void reiserfs_write_unlock(struct super_block *s) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + + /* + * Are we unlocking without even holding the lock? + * Such a situation must raise a BUG() if we don't want + * to corrupt the data. + */ + BUG_ON(sb_i->lock_owner != current); + + if (--sb_i->lock_depth == -1) { + sb_i->lock_owner = NULL; + mutex_unlock(&sb_i->lock); + } +} + +int __must_check reiserfs_write_unlock_nested(struct super_block *s) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + int depth; + + /* this can happen when the lock isn't always held */ + if (sb_i->lock_owner != current) + return -1; + + depth = sb_i->lock_depth; + + sb_i->lock_depth = -1; + sb_i->lock_owner = NULL; + mutex_unlock(&sb_i->lock); + + return depth; +} + +void reiserfs_write_lock_nested(struct super_block *s, int depth) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + + /* this can happen when the lock isn't always held */ + if (depth == -1) + return; + + mutex_lock(&sb_i->lock); + sb_i->lock_owner = current; + sb_i->lock_depth = depth; +} + +/* + * Utility function to force a BUG if it is called without the superblock + * write lock held. caller is the string printed just before calling BUG() + */ +void reiserfs_check_lock_depth(struct super_block *sb, char *caller) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(sb); + + WARN_ON(sb_i->lock_depth < 0); +} + +#ifdef CONFIG_REISERFS_CHECK +void reiserfs_lock_check_recursive(struct super_block *sb) +{ + struct reiserfs_sb_info *sb_i = REISERFS_SB(sb); + + WARN_ONCE((sb_i->lock_depth > 0), "Unwanted recursive reiserfs lock!\n"); +} +#endif -- cgit v1.2.3