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Darwish" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] vfs: Use sequence counter with associated spinlock Cc: "Ahmed S. Darwish" , "Peter Zijlstra (Intel)" , x86 , LKML In-Reply-To: <20200720155530.1173732-19-a.darwish@linutronix.de> References: <20200720155530.1173732-19-a.darwish@linutronix.de> MIME-Version: 1.0 Message-ID: <159603321115.4006.2959071495422039396.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: 26475371976c69489d3a8e6c8bbf35afbbc25055 Gitweb: https://git.kernel.org/tip/26475371976c69489d3a8e6c8bbf35afbbc25055 Author: Ahmed S. Darwish AuthorDate: Mon, 20 Jul 2020 17:55:24 +02:00 Committer: Peter Zijlstra CommitterDate: Wed, 29 Jul 2020 16:14:27 +02:00 vfs: Use sequence counter with associated spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-19-a.darwish@linutronix.de --- fs/dcache.c | 2 +- fs/fs_struct.c | 4 ++-- include/linux/dcache.h | 2 +- include/linux/fs_struct.h | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 361ea7a..ea04858 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1746,7 +1746,7 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) dentry->d_lockref.count = 1; dentry->d_flags = 0; spin_lock_init(&dentry->d_lock); - seqcount_init(&dentry->d_seq); + seqcount_spinlock_init(&dentry->d_seq, &dentry->d_lock); dentry->d_inode = NULL; dentry->d_parent = dentry; dentry->d_sb = sb; diff --git a/fs/fs_struct.c b/fs/fs_struct.c index ca639ed..04b3f5b 100644 --- a/fs/fs_struct.c +++ b/fs/fs_struct.c @@ -117,7 +117,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old) fs->users = 1; fs->in_exec = 0; spin_lock_init(&fs->lock); - seqcount_init(&fs->seq); + seqcount_spinlock_init(&fs->seq, &fs->lock); fs->umask = old->umask; spin_lock(&old->lock); @@ -163,6 +163,6 @@ EXPORT_SYMBOL(current_umask); struct fs_struct init_fs = { .users = 1, .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), - .seq = SEQCNT_ZERO(init_fs.seq), + .seq = SEQCNT_SPINLOCK_ZERO(init_fs.seq, &init_fs.lock), .umask = 0022, }; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index a81f0c3..65d975b 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -89,7 +89,7 @@ extern struct dentry_stat_t dentry_stat; struct dentry { /* RCU lookup touched fields */ unsigned int d_flags; /* protected by d_lock */ - seqcount_t d_seq; /* per dentry seqlock */ + seqcount_spinlock_t d_seq; /* per dentry seqlock */ struct hlist_bl_node d_hash; /* lookup hash list */ struct dentry *d_parent; /* parent directory */ struct qstr d_name; diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h index cf1015a..783b48d 100644 --- a/include/linux/fs_struct.h +++ b/include/linux/fs_struct.h @@ -9,7 +9,7 @@ struct fs_struct { int users; spinlock_t lock; - seqcount_t seq; + seqcount_spinlock_t seq; int umask; int in_exec; struct path root, pwd;