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 v3 - Added comments to clarify semantic changes in fuse_reverse_inval_inode() when called with FUSE_INVAL_ALL_INODES (suggested by Bernd). - Added comments to inodes iteration loop to clarify __iget/iput usage (suggested by Joanne) - Dropped get_fuse_mount() call -- fuse_mount can be obtained from fuse_ilookup() directly (suggested by Joanne) (Also dropped the RFC from the subject.) * 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 | 83 +++++++++++++++++++++++++++++++++++---- include/uapi/linux/fuse.h | 3 ++ 2 files changed, 79 insertions(+), 7 deletions(-) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index e9db2cb8c150..5aa49856731a 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -547,25 +547,94 @@ 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, &fm); + if (!inode || !fm) + return -ENOENT; + + iput(inode); + 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)) { + spin_unlock(&inode->i_lock); + continue; + } + + /* + * This __iget()/iput() dance is required so that we can release + * the sb lock and continue the iteration on the previous + * inode. If we don't keep a ref to the old inode it could have + * disappear. This way we can safely call cond_resched() when + * there's a huge amount of inodes to iterate. + */ + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(&sb->s_inode_list_lock); + iput(old_inode); + + inval_single_inode(inode, fc); + + old_inode = inode; + cond_resched(); + spin_lock(&sb->s_inode_list_lock); + } + spin_unlock(&sb->s_inode_list_lock); + iput(old_inode); + + shrink_dcache_sb(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) { - 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
