From 850d71acd52cd331474116fbd60cf8b3f3ded93e Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 17 Sep 2019 23:31:27 -0400 Subject: autofs: don't bother with atomics for ino->count All writers are serialized on inode->i_rwsem. So are the readers outside of expire.c. And the readers in expire.c are in the code that really doesn't care about narrow races - it's looking for expiry candidates and its callers have to cope with the possibility of a good candidate becoming busy right under them. No point bothering with atomic operations - just use int and mark the non-serialized readers with READ_ONCE(). Signed-off-by: Al Viro --- fs/autofs/autofs_i.h | 2 +- fs/autofs/expire.c | 6 +++--- fs/autofs/root.c | 20 ++++++++++---------- 3 files changed, 14 insertions(+), 14 deletions(-) diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h index 8bcec8dcabb6..054f97b07754 100644 --- a/fs/autofs/autofs_i.h +++ b/fs/autofs/autofs_i.h @@ -63,7 +63,7 @@ struct autofs_info { struct autofs_sb_info *sbi; unsigned long last_used; - atomic_t count; + int count; kuid_t uid; kgid_t gid; diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c index 2866fabf497f..31d616aa6fc9 100644 --- a/fs/autofs/expire.c +++ b/fs/autofs/expire.c @@ -211,7 +211,7 @@ static int autofs_tree_busy(struct vfsmount *mnt, } } else { struct autofs_info *ino = autofs_dentry_ino(p); - unsigned int ino_count = atomic_read(&ino->count); + unsigned int ino_count = READ_ONCE(ino->count); /* allow for dget above and top is already dgot */ if (p == top) @@ -379,7 +379,7 @@ static struct dentry *should_expire(struct dentry *dentry, /* Not a forced expire? */ if (!(how & AUTOFS_EXP_FORCED)) { /* ref-walk currently on this dentry? */ - ino_count = atomic_read(&ino->count) + 1; + ino_count = READ_ONCE(ino->count) + 1; if (d_count(dentry) > ino_count) return NULL; } @@ -396,7 +396,7 @@ static struct dentry *should_expire(struct dentry *dentry, /* Not a forced expire? */ if (!(how & AUTOFS_EXP_FORCED)) { /* ref-walk currently on this dentry? */ - ino_count = atomic_read(&ino->count) + 1; + ino_count = READ_ONCE(ino->count) + 1; if (d_count(dentry) > ino_count) return NULL; } diff --git a/fs/autofs/root.c b/fs/autofs/root.c index ae1d112b6f64..5aaa1732bf1e 100644 --- a/fs/autofs/root.c +++ b/fs/autofs/root.c @@ -569,9 +569,9 @@ static int autofs_dir_symlink(struct inode *dir, d_add(dentry, inode); dget(dentry); - atomic_inc(&ino->count); + ino->count++; p_ino = autofs_dentry_ino(dentry->d_parent); - atomic_inc(&p_ino->count); + p_ino->count++; dir->i_mtime = current_time(dir); @@ -609,9 +609,9 @@ static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry) if (sbi->flags & AUTOFS_SBI_CATATONIC) return -EACCES; - atomic_dec(&ino->count); + ino->count--; p_ino = autofs_dentry_ino(dentry->d_parent); - atomic_dec(&p_ino->count); + p_ino->count--; dput(ino->dentry); d_inode(dentry)->i_size = 0; @@ -669,7 +669,7 @@ static void autofs_clear_leaf_automount_flags(struct dentry *dentry) /* only consider parents below dentrys in the root */ if (IS_ROOT(parent->d_parent)) return; - if (atomic_read(&autofs_dentry_ino(parent)->count) == 2) + if (autofs_dentry_ino(parent)->count == 2) managed_dentry_set_managed(parent); } @@ -691,7 +691,7 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry) if (sbi->flags & AUTOFS_SBI_CATATONIC) return -EACCES; - if (atomic_read(&ino->count) != 1) + if (ino->count != 1) return -ENOTEMPTY; spin_lock(&sbi->lookup_lock); @@ -702,9 +702,9 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry) if (sbi->version < 5) autofs_clear_leaf_automount_flags(dentry); - atomic_dec(&ino->count); + ino->count--; p_ino = autofs_dentry_ino(dentry->d_parent); - atomic_dec(&p_ino->count); + p_ino->count--; dput(ino->dentry); d_inode(dentry)->i_size = 0; clear_nlink(d_inode(dentry)); @@ -750,9 +750,9 @@ static int autofs_dir_mkdir(struct inode *dir, autofs_set_leaf_automount_flags(dentry); dget(dentry); - atomic_inc(&ino->count); + ino->count++; p_ino = autofs_dentry_ino(dentry->d_parent); - atomic_inc(&p_ino->count); + p_ino->count++; inc_nlink(dir); dir->i_mtime = current_time(dir); -- cgit v1.2.3-59-g8ed1b