On 2/10/25 6:33 AM, Luis Henriques wrote:
Currently userspace is able to notify the kernel to invalidate the cache
for an inode. This means that, if all the inodes in a filesystem need to
be invalidated, then userspace needs to iterate through all of them and do
this kernel notification separately.
This patch adds a new option that allows userspace to invalidate all the
inodes with a single notification operation. In addition to invalidate all
the inodes, it also shrinks the sb dcache.
Signed-off-by: Luis Henriques <luis@xxxxxxxxxx>
---
* Changes since v2
Use the new helper from fuse_reverse_inval_inode(), as suggested by Bernd.
Also updated patch description as per checkpatch.pl suggestion.
* Changes since v1
As suggested by Bernd, this patch v2 simply adds an helper function that
will make it easier to replace most of it's code by a call to function
super_iter_inodes() when Dave Chinner's patch[1] eventually gets merged.
[1] https://lore.kernel.org/r/20241002014017.3801899-3-david@xxxxxxxxxxxxx
fs/fuse/inode.c | 67 +++++++++++++++++++++++++++++++++++----
include/uapi/linux/fuse.h | 3 ++
2 files changed, 63 insertions(+), 7 deletions(-)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index e9db2cb8c150..45b9fbb54d42 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -547,25 +547,78 @@ struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
return NULL;
}
+static void inval_single_inode(struct inode *inode, struct fuse_conn *fc)
+{
+ struct fuse_inode *fi;
+
+ fi = get_fuse_inode(inode);
+ spin_lock(&fi->lock);
+ fi->attr_version = atomic64_inc_return(&fc->attr_version);
+ spin_unlock(&fi->lock);
+ fuse_invalidate_attr(inode);
+ forget_all_cached_acls(inode);
+}
+
+static int fuse_reverse_inval_all(struct fuse_conn *fc)
+{
+ struct fuse_mount *fm;
+ struct super_block *sb;
+ struct inode *inode, *old_inode = NULL;
+
+ inode = fuse_ilookup(fc, FUSE_ROOT_ID, NULL);
+ if (!inode)
+ return -ENOENT;
+
+ fm = get_fuse_mount(inode);
I think if you pass in &fm as the 3rd arg to fuse_ilookup(), it'll pass
back the fuse mount and we won't need get_fuse_mount().
+ iput(inode);
+ if (!fm)
+ return -ENOENT;
+ sb = fm->sb;
+
+ spin_lock(&sb->s_inode_list_lock);
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ spin_lock(&inode->i_lock);
+ if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
+ !atomic_read(&inode->i_count)) {
Will inode->i_count ever be 0? AFAIU, inode->i_count tracks the inode
refcount, so if this is 0, doesn't this mean it wouldn't be on the
sb->s_inodes list?
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
+
+ __iget(inode);
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&sb->s_inode_list_lock);
Maybe worth adding a comment here since there can be inodes added after
the s_inode_list_lock is dropped and before it's acquired again that
when inodes get added to the head of sb->s_inodes, it's always for I_NEW
inodes.
+ iput(old_inode);
Maybe a dumb question but why is old_inode needed? Why can't iput()just
be called right after inval_single_inode()?
+
+ inval_single_inode(inode, fc);
+
+ old_inode = inode;
+ cond_resched();
Could you explain why a cond_resched() is needed here?
+ spin_lock(&sb->s_inode_list_lock);
+ }
+ spin_unlock(&sb->s_inode_list_lock);
+ iput(old_inode);
+
+ shrink_dcache_sb(sb);
+
+ return 0;
+}
+
Thanks,
Joanne
int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
loff_t offset, loff_t len)
{
- struct fuse_inode *fi;
struct inode *inode;
pgoff_t pg_start;
pgoff_t pg_end;
+ if (nodeid == FUSE_INVAL_ALL_INODES)
+ return fuse_reverse_inval_all(fc);
+
inode = fuse_ilookup(fc, nodeid, NULL);
if (!inode)
return -ENOENT;
- fi = get_fuse_inode(inode);
- spin_lock(&fi->lock);
- fi->attr_version = atomic64_inc_return(&fc->attr_version);
- spin_unlock(&fi->lock);
+ inval_single_inode(inode, fc);
- fuse_invalidate_attr(inode);
- forget_all_cached_acls(inode);
if (offset >= 0) {
pg_start = offset >> PAGE_SHIFT;
if (len <= 0)
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 5e0eb41d967e..e5852b63f99f 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -669,6 +669,9 @@ enum fuse_notify_code {
FUSE_NOTIFY_CODE_MAX,
};
+/* The nodeid to request to invalidate all inodes */
+#define FUSE_INVAL_ALL_INODES 0
+
/* The read buffer is required to be at least 8k, but may be much larger */
#define FUSE_MIN_READ_BUFFER 8192
