On 2/16/25 17:50, 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>
> ---
> fs/fuse/inode.c | 33 +++++++++++++++++++++++++++++++++
> include/uapi/linux/fuse.h | 3 +++
> 2 files changed, 36 insertions(+)
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index e9db2cb8c150..01a4dc5677ae 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -547,6 +547,36 @@ struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
> return NULL;
> }
>
> +static int fuse_reverse_inval_all(struct fuse_conn *fc)
> +{
> + struct fuse_mount *fm;
> + struct inode *inode;
> +
> + inode = fuse_ilookup(fc, FUSE_ROOT_ID, &fm);
> + if (!inode || !fm)
> + return -ENOENT;
> +
> + /* Remove all possible active references to cached inodes */
> + shrink_dcache_sb(fm->sb);
> +
> + /* Remove all unreferenced inodes from cache */
> + invalidate_inodes(fm->sb);
> +
> + return 0;
> +}
> +
> +/*
> + * Notify to invalidate inodes cache. It can be called with @nodeid set to
> + * either:
> + *
> + * - An inode number - Any pending writebacks within the rage [@offset @len]
> + * will be triggered and the inode will be validated. To invalidate the whole
> + * cache @offset has to be set to '0' and @len needs to be <= '0'; if @offset
> + * is negative, only the inode attributes are invalidated.
> + *
> + * - FUSE_INVAL_ALL_INODES - All the inodes in the superblock are invalidated
> + * and the whole dcache is shrinked.
> + */
> int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
> loff_t offset, loff_t len)
> {
> @@ -555,6 +585,9 @@ int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
> 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;
> 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
>
I think this version might end up in
static void fuse_evict_inode(struct inode *inode)
{
struct fuse_inode *fi = get_fuse_inode(inode);
/* Will write inode on close/munmap and in all other dirtiers */
WARN_ON(inode->i_state & I_DIRTY_INODE);
if the fuse connection has writeback cache enabled.
Without having it tested, reproducer would probably be to run
something like passthrough_hp (without --direct-io), opening
and writing to a file and then sending FUSE_INVAL_ALL_INODES.
Thanks,
Bernd
