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-rw-r--r--fs/nfs/inode.c44
1 files changed, 41 insertions, 3 deletions
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index f189169348b..8c514a1353c 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -948,11 +948,49 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
return 0;
}
-static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
+static int nfs_ctime_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
{
- struct nfs_inode *nfsi = NFS_I(inode);
+ return timespec_compare(&fattr->ctime, &inode->i_ctime) > 0;
+}
+
+static int nfs_size_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
+{
+ return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
+}
- if (time_after(fattr->time_start, nfsi->last_updated))
+/**
+ * nfs_inode_attrs_need_update - check if the inode attributes need updating
+ * @inode - pointer to inode
+ * @fattr - attributes
+ *
+ * Attempt to divine whether or not an RPC call reply carrying stale
+ * attributes got scheduled after another call carrying updated ones.
+ *
+ * To do so, the function first assumes that a more recent ctime means
+ * that the attributes in fattr are newer, however it also attempt to
+ * catch the case where ctime either didn't change, or went backwards
+ * (if someone reset the clock on the server) by looking at whether
+ * or not this RPC call was started after the inode was last updated.
+ * Note also the check for jiffy wraparound if the last_updated timestamp
+ * is later than 'jiffies'.
+ *
+ * The function returns 'true' if it thinks the attributes in 'fattr' are
+ * more recent than the ones cached in the inode.
+ *
+ */
+static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
+{
+ const struct nfs_inode *nfsi = NFS_I(inode);
+
+ return nfs_ctime_need_update(inode, fattr) ||
+ nfs_size_need_update(inode, fattr) ||
+ time_after(fattr->time_start, nfsi->last_updated) ||
+ time_after(nfsi->last_updated, jiffies);
+}
+
+static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
+{
+ if (nfs_inode_attrs_need_update(inode, fattr))
return nfs_update_inode(inode, fattr);
return nfs_check_inode_attributes(inode, fattr);
}