linux-kernel - [PATCH] fuse: invalidate dentry on EEXIST creates or ENOENT deletes

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Message-Id: <20220805131823.83544-1-zhangjiachen.jaycee@bytedance.com>
Date:   Fri,  5 Aug 2022 21:18:22 +0800
From:   Jiachen Zhang <zhangjiachen.jaycee@...edance.com>
To:     Miklos Szeredi <miklos@...redi.hu>,
        linux-fsdevel@...r.kernel.org (open list:FUSE: FILESYSTEM IN USERSPACE),
        linux-kernel@...r.kernel.org (open list)
Cc:     Jiachen Zhang <zhangjiachen.jaycee@...edance.com>
Subject: [PATCH] fuse: invalidate dentry on EEXIST creates or ENOENT deletes

If kernel creates a file which already exists on the server (EEXIST), we'd
better invalidate its negative dentry cache. Similarly, if kernel wants
to delete a file that is already deleted on the server (ENOENT), we can
also invalidate its positive dentry cache. This commit does this by
setting the fuse dentry timeout to 0 using fuse_invalidate_entry().

Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@...edance.com>
---
 fs/fuse/dir.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 74303d6e987b..3bb34a849831 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -669,7 +669,8 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
 	if (err == -ENOSYS) {
 		fc->no_create = 1;
 		goto mknod;
-	}
+	} else if (err == -EEXIST)
+		fuse_invalidate_entry(entry);
 out_dput:
 	dput(res);
 	return err;
@@ -758,6 +759,8 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args,
 	return 0;
 
  out_put_forget_req:
+	if (err == -EEXIST)
+		fuse_invalidate_entry(entry);
 	kfree(forget);
 	return err;
 }
@@ -892,7 +895,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 	if (!err) {
 		fuse_dir_changed(dir);
 		fuse_entry_unlinked(entry);
-	} else if (err == -EINTR)
+	} else if (err == -EINTR || err == -ENOENT)
 		fuse_invalidate_entry(entry);
 	return err;
 }
@@ -915,7 +918,7 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 	if (!err) {
 		fuse_dir_changed(dir);
 		fuse_entry_unlinked(entry);
-	} else if (err == -EINTR)
+	} else if (err == -EINTR || err == -ENOENT)
 		fuse_invalidate_entry(entry);
 	return err;
 }
@@ -956,7 +959,7 @@ static int fuse_rename_common(struct inode *olddir, struct dentry *oldent,
 		/* newent will end up negative */
 		if (!(flags & RENAME_EXCHANGE) && d_really_is_positive(newent))
 			fuse_entry_unlinked(newent);
-	} else if (err == -EINTR) {
+	} else if (err == -EINTR || err == -ENOENT) {
 		/* If request was interrupted, DEITY only knows if the
 		   rename actually took place.  If the invalidation
 		   fails (e.g. some process has CWD under the renamed
-- 
2.20.1