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From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Chandan Rajendra <chandan@linux.vnet.ibm.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	linux-unionfs@vger.kernel.org
Subject: [PATCH v6 8/9] ovl: update merge dir cache for non-samefs case
Date: Wed,  1 Nov 2017 22:22:52 +0200	[thread overview]
Message-ID: <1509567773-25590-9-git-send-email-amir73il@gmail.com> (raw)
In-Reply-To: <1509567773-25590-1-git-send-email-amir73il@gmail.com>

st_ino returned by stat(2) for dirs on non-samefs is the non persistent
overlay i_ino. Update the dir cache with volatile overlay i_ino values.
Overlay dir cache and inode cache may get out of sync after child inodes
exit and re-enter inode cache. This means that user may see inconsistent
st_ino/d_ino, but user can already see inconsistent st_ino of same object
in different times, so this is better than nothing.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/overlayfs/readdir.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 74b859ed569e..fa1be3fe68fa 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -120,6 +120,10 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
 	if (!rdd->dentry)
 		return false;
 
+	/* Always recalc d_ino from i_ino for dir on non-samefs */
+	if (p->type == DT_DIR && !ovl_same_sb(rdd->dentry->d_sb))
+		return true;
+
 	/* Always recalc d_ino for parent */
 	if (strcmp(p->name, "..") == 0)
 		return true;
@@ -480,6 +484,19 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
 	}
 
 get:
+	/*
+	 * st_ino for dirs on non-samefs is the non persistent overlay i_ino.
+	 * Update the dir cache with volatile overlay i_ino, even though
+	 * dir cache and inode cache may get out of sync after child inodes
+	 * exit and re-enter inode cache. This means that user may see
+	 * inconsistent st_ino/d_ino, but user can already see inconsistent
+	 * st_ino of same object in different times.
+	 */
+	if (p->type == DT_DIR && !ovl_same_sb(dir->d_sb)) {
+		ino = this->d_inode->i_ino;
+		goto out;
+	}
+
 	type = ovl_path_type(this);
 	if (OVL_TYPE_ORIGIN(type)) {
 		struct kstat stat;
@@ -489,7 +506,7 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
 		err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
 		if (err)
 			goto fail;
-		if (d_is_dir(this) || ovl_same_sb(this->d_sb))
+		if (ovl_same_sb(dir->d_sb))
 			WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
 		ino = stat.ino;
 	}
-- 
2.7.4

  parent reply	other threads:[~2017-11-01 20:22 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-01 20:22 [PATCH v6 0/9] Overlayfs: constant st_ino/d_ino for non-samefs Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 1/9] ovl: move include of ovl_entry.h into overlayfs.h Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 2/9] ovl: re-structure overlay lower layers in-memory Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 3/9] ovl: allocate anonymous devs for lowerdirs Amir Goldstein
2017-11-02 12:28   ` Vivek Goyal
2017-11-02 13:05     ` Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 4/9] ovl: return anonymous st_dev for lower inodes Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 5/9] ovl: relax same fs constraint for constant st_ino Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 6/9] ovl: fix d_ino of current pure upper in non-samefs case Amir Goldstein
2017-11-01 20:22 ` [PATCH v6 7/9] ovl: update cache version of impure parent on rename Amir Goldstein
2017-11-01 20:22 ` Amir Goldstein [this message]
2017-11-01 20:22 ` [PATCH v6 9/9] ovl: update non-merge dir cache for non-samefs case Amir Goldstein
2017-11-02 16:33 ` [PATCH v6 0/9] Overlayfs: constant st_ino/d_ino for non-samefs Miklos Szeredi
2017-11-02 18:06   ` Amir Goldstein

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