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proc: In proc_prune_siblings_dcache cache an aquired super block 

Because there are likely to be several sysctls in a row on the
same superblock cache the super_block after the count has
been raised and don't deactivate it until we are processing
another super_block.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
alistair/sensors
Eric W. Biederman 2020-02-21 08:33:57 -06:00
parent 26dbc60f38
commit 080f6276fc
1 changed files with 10 additions and 4 deletions
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14
fs/proc/inode.c
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@ -108,10 +108,11 @@ void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
struct inode *inode; struct inode *inode;
struct proc_inode *ei; struct proc_inode *ei;
struct hlist_node *node; struct hlist_node *node;
struct super_block *sb; struct super_block *old_sb = NULL;
rcu_read_lock(); rcu_read_lock();
for (;;) { for (;;) {
struct super_block *sb;
node = hlist_first_rcu(inodes); node = hlist_first_rcu(inodes);
if (!node) if (!node)
break; break;
@ -122,23 +123,28 @@ void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
inode = &ei->vfs_inode; inode = &ei->vfs_inode;
sb = inode->i_sb; sb = inode->i_sb;
if (!atomic_inc_not_zero(&sb->s_active)) if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
continue; continue;
inode = igrab(inode); inode = igrab(inode);
rcu_read_unlock(); rcu_read_unlock();
if (sb != old_sb) {
if (old_sb)
deactivate_super(old_sb);
old_sb = sb;
}
if (unlikely(!inode)) { if (unlikely(!inode)) {
deactivate_super(sb);
rcu_read_lock(); rcu_read_lock();
continue; continue;
} }
d_prune_aliases(inode); d_prune_aliases(inode);
iput(inode); iput(inode);
deactivate_super(sb);
rcu_read_lock(); rcu_read_lock();
} }
rcu_read_unlock(); rcu_read_unlock();
if (old_sb)
deactivate_super(old_sb);
} }
static int proc_show_options(struct seq_file *seq, struct dentry *root) static int proc_show_options(struct seq_file *seq, struct dentry *root)