fuse/md-cache: add support for the 'fopen-keep-cache' mount option

fopen-keep-cache disables unconditional page-cache invalidations
on file open in fuse (via FOPEN_KEEP_CACHE) and replaces that
behavior with detection of remote changes and explicit
invalidations from mount/fuse. This option improves local caching
through the page cache and native client.

This change defines a new 'invalidate' translator callback to
identify when an inode's cache mapping has been determined to be
invalid. md-cache implements the policy to detect and invoke
inode invalidations. fuse-bridge and io-cache implement
invalidate handlers to invalidate the respective caches (page
cache in the case of fuse).

BUG: 833564
Change-Id: I99818da5777eaf06276c1c0b194669f5bab92d48
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.com/3584
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 25 insertions, 7 deletions

diff --git a/xlators/performance/md-cache/src/md-cache.c b/xlators/performance/md-cache/src/md-cache.c
index 9acffba2a..cf1aee9d6 100644
--- a/xlators/performance/md-cache/src/md-cache.c
+++ b/xlators/performance/md-cache/src/md-cache.c
@@ -378,7 +378,8 @@ mdc_to_iatt (struct md_cache *mdc, struct iatt *iatt)
 
 
 int
-mdc_inode_iatt_set (xlator_t *this, inode_t *inode, struct iatt *iatt)
+mdc_inode_iatt_set_validate(xlator_t *this, inode_t *inode, struct iatt *prebuf,
+			    struct iatt *iatt)
 {
         int              ret = -1;
         struct md_cache *mdc = NULL;
@@ -394,6 +395,19 @@ mdc_inode_iatt_set (xlator_t *this, inode_t *inode, struct iatt *iatt)
                         goto unlock;
                 }
 
+		/*
+		 * Invalidate the inode if the mtime or ctime has changed
+		 * and the prebuf doesn't match the value we have cached.
+		 * TODO: writev returns with a NULL iatt due to
+		 * performance/write-behind, causing invalidation on writes.
+		 */
+		if (IA_ISREG(inode->ia_type) &&
+		    ((iatt->ia_mtime != mdc->md_mtime) ||
+		    (iatt->ia_ctime != mdc->md_ctime)))
+			if (!prebuf || (prebuf->ia_ctime != mdc->md_ctime) ||
+			    (prebuf->ia_mtime != mdc->md_mtime))
+				inode_invalidate(inode);
+
                 mdc_from_iatt (mdc, iatt);
 
                 time (&mdc->ia_time);
@@ -405,6 +419,10 @@ out:
         return ret;
 }
 
+int mdc_inode_iatt_set(xlator_t *this, inode_t *inode, struct iatt *iatt)
+{
+	return mdc_inode_iatt_set_validate(this, inode, NULL, iatt);
+}
 
 int
 mdc_inode_iatt_get (xlator_t *this, inode_t *inode, struct iatt *iatt)
@@ -859,7 +877,7 @@ mdc_truncate_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->loc.inode, postbuf);
+        mdc_inode_iatt_set_validate(this, local->loc.inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (truncate, frame, op_ret, op_errno, prebuf, postbuf,
@@ -901,7 +919,7 @@ mdc_ftruncate_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->fd->inode, postbuf);
+        mdc_inode_iatt_set_validate(this, local->fd->inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (ftruncate, frame, op_ret, op_errno, prebuf, postbuf,
@@ -1377,7 +1395,7 @@ mdc_writev_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->fd->inode, postbuf);
+        mdc_inode_iatt_set_validate(this, local->fd->inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (writev, frame, op_ret, op_errno, prebuf, postbuf,
@@ -1422,7 +1440,7 @@ mdc_setattr_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->loc.inode, postbuf);
+	mdc_inode_iatt_set_validate(this, local->loc.inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (setattr, frame, op_ret, op_errno, prebuf, postbuf,
@@ -1464,7 +1482,7 @@ mdc_fsetattr_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->fd->inode, postbuf);
+        mdc_inode_iatt_set_validate(this, local->fd->inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (fsetattr, frame, op_ret, op_errno, prebuf, postbuf,
@@ -1506,7 +1524,7 @@ mdc_fsync_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         if (!local)
                 goto out;
 
-        mdc_inode_iatt_set (this, local->fd->inode, postbuf);
+        mdc_inode_iatt_set_validate(this, local->fd->inode, prebuf, postbuf);
 
 out:
         MDC_STACK_UNWIND (fsync, frame, op_ret, op_errno, prebuf, postbuf,