Re: [RFC PATCH V6 4/7] ovl: set 'DONTCACHE' flag for overlayfs inode
From: Jan Kara <jack@suse.cz>
Date: 2021-11-26 09:22:26
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linux-fsdevel, lkml
On Mon 22-11-21 11:00:35, Chengguang Xu wrote:
quoted hunk ↗ jump to hunk
From: Chengguang Xu <redacted> Set 'DONTCACHE' flag to overlayfs inode so that upper inode to be always synced before eviction. Signed-off-by: Chengguang Xu <redacted> --- fs/overlayfs/inode.c | 1 + 1 file changed, 1 insertion(+)diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 027ffc0a2539..c4472299d5df 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c@@ -791,6 +791,7 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip, ovl_copyattr(realinode, inode); ovl_copyflags(realinode, inode); ovl_map_ino(inode, ino, fsid); + d_mark_dontcache(inode); }
Doesn't this effectively disable dcache for overlayfs dentries? I mean e.g. whenever overlayfs file is closed, we will drop its dentry & inode from the cache. Upper and lower inodes / dentries stay in cache so no disk access should be needed to reconstruct overlayfs dentry & inode but still it may be a bit costly? I guess others more familiar with overlayfs have to judge. Honza -- Jan Kara [off-list ref] SUSE Labs, CR