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Subject: [PATCH 29/67] cachefiles: Trace read and write operations
From:   David Howells <dhowells@redhat.com>
To:     linux-cachefs@redhat.com
Cc:     dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Steve French <sfrench@samba.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Jeff Layton <jlayton@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Omar Sandoval <osandov@osandov.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
        linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
        v9fs-developer@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 18 Oct 2021 15:57:52 +0100
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In-Reply-To: <163456861570.2614702.14754548462706508617.stgit@warthog.procyon.org.uk>
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Add tracepoints for read and write operations on cache files.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/io.c                |    6 +++-
 include/trace/events/cachefiles.h |   58 +++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 0e1fb44b5d04..f703a93e238b 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -62,6 +62,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
 			   netfs_io_terminated_t term_func,
 			   void *term_func_priv)
 {
+	struct cachefiles_object *object = cres->cache_priv;
 	struct cachefiles_kiocb *ki;
 	struct file *file = cachefiles_cres_file(cres);
 	unsigned int old_nofs;
@@ -124,6 +125,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
 
 	get_file(ki->iocb.ki_filp);
 
+	trace_cachefiles_read(object, file_inode(file), ki->iocb.ki_pos, len - skipped);
 	old_nofs = memalloc_nofs_save();
 	ret = vfs_iocb_iter_read(file, &ki->iocb, iter);
 	memalloc_nofs_restore(old_nofs);
@@ -188,6 +190,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
 			    netfs_io_terminated_t term_func,
 			    void *term_func_priv)
 {
+	struct cachefiles_object *object = cres->cache_priv;
 	struct cachefiles_kiocb *ki;
 	struct inode *inode;
 	struct file *file = cachefiles_cres_file(cres);
@@ -229,6 +232,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
 
 	get_file(ki->iocb.ki_filp);
 
+	trace_cachefiles_write(object, inode, ki->iocb.ki_pos, len);
 	old_nofs = memalloc_nofs_save();
 	ret = vfs_iocb_iter_write(file, &ki->iocb, iter);
 	memalloc_nofs_restore(old_nofs);
@@ -418,7 +422,7 @@ int cachefiles_begin_operation(struct netfs_cache_resources *cres)
 
 	_enter("");
 
-	cres->cache_priv	= op;
+	cres->cache_priv	= object;
 	cres->cache_priv2	= get_file(object->file);
 	cres->ops		= &cachefiles_netfs_cache_ops;
 	cres->debug_id		= object->cookie->debug_id;
diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h
index 09d76c160451..47df44550ad6 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -302,6 +302,64 @@ TRACE_EVENT(cachefiles_coherency,
 		      __entry->content)
 	    );
 
+TRACE_EVENT(cachefiles_read,
+	    TP_PROTO(struct cachefiles_object *obj,
+		     struct inode *backer,
+		     loff_t start,
+		     size_t len),
+
+	    TP_ARGS(obj, backer, start, len),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,			obj	)
+		    __field(unsigned int,			backer	)
+		    __field(size_t,				len	)
+		    __field(loff_t,				start	)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->obj	= obj->debug_id;
+		    __entry->backer	= backer->i_ino;
+		    __entry->start	= start;
+		    __entry->len	= len;
+			   ),
+
+	    TP_printk("o=%08x b=%08x s=%llx l=%zx",
+		      __entry->obj,
+		      __entry->backer,
+		      __entry->start,
+		      __entry->len)
+	    );
+
+TRACE_EVENT(cachefiles_write,
+	    TP_PROTO(struct cachefiles_object *obj,
+		     struct inode *backer,
+		     loff_t start,
+		     size_t len),
+
+	    TP_ARGS(obj, backer, start, len),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,			obj	)
+		    __field(unsigned int,			backer	)
+		    __field(size_t,				len	)
+		    __field(loff_t,				start	)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->obj	= obj->debug_id;
+		    __entry->backer	= backer->i_ino;
+		    __entry->start	= start;
+		    __entry->len	= len;
+			   ),
+
+	    TP_printk("o=%08x b=%08x s=%llx l=%zx",
+		      __entry->obj,
+		      __entry->backer,
+		      __entry->start,
+		      __entry->len)
+	    );
+
 TRACE_EVENT(cachefiles_trunc,
 	    TP_PROTO(struct cachefiles_object *obj, struct inode *backer,
 		     loff_t from, loff_t to, enum cachefiles_trunc_trace why),