Commit 169379ea authored by David Howells's avatar David Howells
Browse files

cachefiles: Mark a backing file in use with an inode flag 



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: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
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
Link: https://lore.kernel.org/r/164021541207.640689.564689725898537127.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/164021552299.640689.10578652796777392062.stgit@warthog.procyon.org.uk/ # v4
parent 72b95785

fs/cachefiles/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

fs/cachefiles/namei.c

+35 −0
Original line number Diff line number Diff line
@@ -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

 */