| Message ID | 20240611120626.513952-3-mjguzik@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | inode_init_always zeroing i_state | expand |
On Tue 11-06-24 14:06:24, Mateusz Guzik wrote: > new_inode used to have the following: > spin_lock(&inode_lock); > inodes_stat.nr_inodes++; > list_add(&inode->i_list, &inode_in_use); > list_add(&inode->i_sb_list, &sb->s_inodes); > inode->i_ino = ++last_ino; > inode->i_state = 0; > spin_unlock(&inode_lock); > > over time things disappeared, got moved around or got replaced (global > inode lock with a per-inode lock), eventually this got reduced to: > spin_lock(&inode->i_lock); > inode->i_state = 0; > spin_unlock(&inode->i_lock); > > But the lock acquire here does not synchronize against anyone. > > Additionally iget5_locked performs i_state = 0 assignment without any > locks to begin with, the two combined look confusing at best. > > It looks like the current state is a leftover which was not cleaned up. > > Ideally it would be an invariant that i_state == 0 to begin with, but > achieving that would require dealing with all filesystem alloc handlers > one by one. > > In the meantime drop the misleading locking and move i_state zeroing to > inode_init_always so that others don't need to deal with it by hand. > > Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Just one nit below: > diff --git a/fs/inode.c b/fs/inode.c > index 3a4c67bfe085..8f05d79de01d 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -231,6 +231,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode) > > if (unlikely(security_inode_alloc(inode))) > return -ENOMEM; > + > + inode->i_state = 0; > this_cpu_inc(nr_inodes); This would be more logical above where inode content is initialized (and less errorprone just in case security_inode_alloc() grows dependency on i_state value) - like just after: inode->i_flags = 0; With that fixed feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza
> This would be more logical above where inode content is initialized (and > less errorprone just in case security_inode_alloc() grows dependency on > i_state value) - like just after: > > inode->i_flags = 0; Fixed that in-tree. Thanks!
diff --git a/fs/inode.c b/fs/inode.c index 3a4c67bfe085..8f05d79de01d 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -231,6 +231,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode) if (unlikely(security_inode_alloc(inode))) return -ENOMEM; + + inode->i_state = 0; this_cpu_inc(nr_inodes); return 0; @@ -1023,14 +1025,7 @@ EXPORT_SYMBOL(get_next_ino); */ struct inode *new_inode_pseudo(struct super_block *sb) { - struct inode *inode = alloc_inode(sb); - - if (inode) { - spin_lock(&inode->i_lock); - inode->i_state = 0; - spin_unlock(&inode->i_lock); - } - return inode; + return alloc_inode(sb); } /** @@ -1254,7 +1249,6 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval, struct inode *new = alloc_inode(sb); if (new) { - new->i_state = 0; inode = inode_insert5(new, hashval, test, set, data); if (unlikely(inode != new)) destroy_inode(new); @@ -1285,7 +1279,6 @@ struct inode *iget5_locked_rcu(struct super_block *sb, unsigned long hashval, struct inode *new = alloc_inode(sb); if (new) { - new->i_state = 0; inode = inode_insert5(new, hashval, test, set, data); if (unlikely(inode != new)) destroy_inode(new);
new_inode used to have the following: spin_lock(&inode_lock); inodes_stat.nr_inodes++; list_add(&inode->i_list, &inode_in_use); list_add(&inode->i_sb_list, &sb->s_inodes); inode->i_ino = ++last_ino; inode->i_state = 0; spin_unlock(&inode_lock); over time things disappeared, got moved around or got replaced (global inode lock with a per-inode lock), eventually this got reduced to: spin_lock(&inode->i_lock); inode->i_state = 0; spin_unlock(&inode->i_lock); But the lock acquire here does not synchronize against anyone. Additionally iget5_locked performs i_state = 0 assignment without any locks to begin with, the two combined look confusing at best. It looks like the current state is a leftover which was not cleaned up. Ideally it would be an invariant that i_state == 0 to begin with, but achieving that would require dealing with all filesystem alloc handlers one by one. In the meantime drop the misleading locking and move i_state zeroing to inode_init_always so that others don't need to deal with it by hand. Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> --- fs/inode.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-)