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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: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff 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
This commit is contained in:
David Howells 2021-11-18 08:58:08 +00:00
parent 72b957856b
commit 169379eaef
2 changed files with 37 additions and 0 deletions
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2
fs/cachefiles/internal.h
View File

@ -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,

35
fs/cachefiles/namei.c
View File

@ -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
*/