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Subject[PATCH 32/37] NFS: Add read context retention for FS-Cache to call back with [ver #34]
Date
Add read context retention so that FS-Cache can call back into NFS when a read
operation on the cache fails EIO rather than reading data. This permits NFS to
then fetch the data from the server instead using the appropriate security
context.

Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/nfs/fscache-index.c | 26 ++++++++++++++++++++++++++
1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/fscache-index.c b/fs/nfs/fscache-index.c
index eec8e7e..af9f06b 100644
--- a/fs/nfs/fscache-index.c
+++ b/fs/nfs/fscache-index.c
@@ -285,6 +285,30 @@ static void nfs_cache_inode_now_uncached(void *cookie_netfs_data)
}

/*
+ * Get an extra reference on a read context.
+ * - This function can be absent if the completion function doesn't require a
+ * context.
+ * - The read context is passed back to NFS in the event that a data read on the
+ * cache fails with EIO - in which case the server must be contacted to
+ * retrieve the data, which requires the read context for security.
+ */
+static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
+{
+ get_nfs_open_context(context);
+}
+
+/*
+ * Release an extra reference on a read context.
+ * - This function can be absent if the completion function doesn't require a
+ * context.
+ */
+static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
+{
+ if (context)
+ put_nfs_open_context(context);
+}
+
+/*
* Define the inode object for FS-Cache. This is used to describe an inode
* object to fscache_acquire_cookie(). It is keyed by the NFS file handle for
* an inode.
@@ -301,4 +325,6 @@ const struct fscache_cookie_def nfs_cache_inode_object_def = {
.get_aux = nfs_cache_inode_get_aux,
.check_aux = nfs_cache_inode_check_aux,
.now_uncached = nfs_cache_inode_now_uncached,
+ .get_context = nfs_fh_get_context,
+ .put_context = nfs_fh_put_context,
};


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