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SubjectRe: [PATCH v4 46/68] cachefiles: Mark a backing file in use with an inode flag
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On Wed, 2021-12-22 at 23:25 +0000, David Howells wrote:
> Use an inode flag, S_KERNEL_FILE, to mark that a backing file is in use by
> the kernel to prevent cachefiles or other kernel services from interfering
> with that file.
>
> Using S_SWAPFILE instead isn't really viable as that has other effects in
> the I/O paths.
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: linux-cachefs@redhat.com
> Link: https://lore.kernel.org/r/163819642273.215744.6414248677118690672.stgit@warthog.procyon.org.uk/ # v1
> Link: https://lore.kernel.org/r/163906943215.143852.16972351425323967014.stgit@warthog.procyon.org.uk/ # v2
> Link: https://lore.kernel.org/r/163967154118.1823006.13227551961786743991.stgit@warthog.procyon.org.uk/ # v3
> ---
>
> fs/cachefiles/internal.h | 2 ++
> fs/cachefiles/namei.c | 35 +++++++++++++++++++++++++++++++++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
> index 01071e7a7c02..7c67a70a3dff 100644
> --- a/fs/cachefiles/internal.h
> +++ b/fs/cachefiles/internal.h
> @@ -187,6 +187,8 @@ extern struct kmem_cache *cachefiles_object_jar;
> /*
> * namei.c
> */
> +extern void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
> + struct file *file);
> extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
> struct dentry *dir,
> const char *name,
> diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
> index 11a33209ab5f..db60a671c3fc 100644
> --- a/fs/cachefiles/namei.c
> +++ b/fs/cachefiles/namei.c
> @@ -31,6 +31,18 @@ static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object,
> return can_use;
> }
>
> +static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object,
> + struct dentry *dentry)
> +{
> + struct inode *inode = d_backing_inode(dentry);
> + bool can_use;
> +
> + inode_lock(inode);
> + can_use = __cachefiles_mark_inode_in_use(object, dentry);
> + inode_unlock(inode);
> + return can_use;
> +}
> +
> /*
> * Unmark a backing inode. The caller must hold the inode lock.
> */
> @@ -43,6 +55,29 @@ static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
> trace_cachefiles_mark_inactive(object, inode);
> }
>
> +/*
> + * Unmark a backing inode and tell cachefilesd that there's something that can
> + * be culled.
> + */
> +void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
> + struct file *file)
> +{
> + struct cachefiles_cache *cache = object->volume->cache;
> + struct inode *inode = file_inode(file);
> +
> + if (inode) {
> + inode_lock(inode);
> + __cachefiles_unmark_inode_in_use(object, file->f_path.dentry);
> + inode_unlock(inode);
> +
> + if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
> + atomic_long_add(inode->i_blocks, &cache->b_released);
> + if (atomic_inc_return(&cache->f_released))
> + cachefiles_state_changed(cache);
> + }
> + }
> +}
> +
> /*
> * get a subdirectory
> */
>
>

Probably, this patch should be merged with #38. The commit logs are the
same, and they are at least somewhat related.

--
Jeff Layton <jlayton@kernel.org>

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