[PATCH v12 3/5] cachefiles: Add a tracepoint to log insufficient space errors

[David Howells <dhowells@redhat.com>]

Add a tracepoint to log insufficient space errors.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
 fs/cachefiles/io.c                | 15 +++++++++++----
 fs/cachefiles/namei.c             | 10 ++++++++--
 include/trace/events/cachefiles.h | 30 +++++++++++++++++++++++++++++-
 3 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index dac48fdf85d1..4b3ceda17426 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -533,10 +533,14 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 	 * space, we need to see if it's fully allocated.  If it's not, we may
 	 * want to cull it.
 	 */
-	if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
-				 cachefiles_has_space_check) == 0)
+	ret = cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+				   cachefiles_has_space_check);
+	if (ret == 0)
 		return 0; /* Enough space to simply overwrite the whole block */
 
+	if (ret == -ENOBUFS)
+		trace_cachefiles_no_space(object, cachefiles_trace_write_nospace_2);
+
 	pos = cachefiles_inject_read_error();
 	if (pos == 0)
 		pos = vfs_llseek(file, start, SEEK_HOLE);
@@ -565,8 +569,11 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
 	return ret;
 
 check_space:
-	return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
-				    cachefiles_has_space_for_write);
+	ret = cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+				   cachefiles_has_space_for_write);
+	if (ret == -ENOBUFS)
+		trace_cachefiles_no_space(object, cachefiles_trace_write_nospace);
+	return ret;
 }
 
 static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 88955249a1a6..4780ce6dc830 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -117,8 +117,11 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 	if (d_is_negative(subdir)) {
 		ret = cachefiles_has_space(cache, 1, 0,
 					   cachefiles_has_space_for_create);
-		if (ret < 0)
+		if (ret < 0) {
+			if (ret == -ENOBUFS)
+				trace_cachefiles_no_space(NULL, cachefiles_trace_mkdir_nospace);
 			goto mkdir_error;
+		}
 
 		_debug("attempt mkdir");
 
@@ -487,8 +490,11 @@ static bool cachefiles_create_file(struct cachefiles_object *object)
 
 	ret = cachefiles_has_space(object->volume->cache, 1, 0,
 				   cachefiles_has_space_for_create);
-	if (ret < 0)
+	if (ret < 0) {
+		if (ret == -ENOBUFS)
+			trace_cachefiles_no_space(object, cachefiles_trace_create_nospace);
 		return false;
+	}
 
 	file = cachefiles_create_tmpfile(object);
 	if (IS_ERR(file))
diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h
index 1938d51a9459..cd865c265c24 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -80,11 +80,13 @@ enum cachefiles_prepare_read_trace {
 };
 
 enum cachefiles_error_trace {
+	cachefiles_trace_create_nospace,
 	cachefiles_trace_fallocate_error,
 	cachefiles_trace_getxattr_error,
 	cachefiles_trace_link_error,
 	cachefiles_trace_lookup_error,
 	cachefiles_trace_mkdir_error,
+	cachefiles_trace_mkdir_nospace,
 	cachefiles_trace_notify_change_error,
 	cachefiles_trace_open_error,
 	cachefiles_trace_read_error,
@@ -97,6 +99,8 @@ enum cachefiles_error_trace {
 	cachefiles_trace_trunc_error,
 	cachefiles_trace_unlink_error,
 	cachefiles_trace_write_error,
+	cachefiles_trace_write_nospace,
+	cachefiles_trace_write_nospace_2,
 };
 
 #endif
@@ -161,11 +165,13 @@ enum cachefiles_error_trace {
 	E_(cachefiles_trace_read_seek_nxio,	"seek-enxio")
 
 #define cachefiles_error_traces						\
+	EM(cachefiles_trace_create_nospace,	"create-nospace")	\
 	EM(cachefiles_trace_fallocate_error,	"fallocate")		\
 	EM(cachefiles_trace_getxattr_error,	"getxattr")		\
 	EM(cachefiles_trace_link_error,		"link")			\
 	EM(cachefiles_trace_lookup_error,	"lookup")		\
 	EM(cachefiles_trace_mkdir_error,	"mkdir")		\
+	EM(cachefiles_trace_mkdir_nospace,	"mkdir-nospace")	\
 	EM(cachefiles_trace_notify_change_error, "notify_change")	\
 	EM(cachefiles_trace_open_error,		"open")			\
 	EM(cachefiles_trace_read_error,		"read")			\
@@ -177,7 +183,9 @@ enum cachefiles_error_trace {
 	EM(cachefiles_trace_tmpfile_error,	"tmpfile")		\
 	EM(cachefiles_trace_trunc_error,	"trunc")		\
 	EM(cachefiles_trace_unlink_error,	"unlink")		\
-	E_(cachefiles_trace_write_error,	"write")
+	EM(cachefiles_trace_write_error,	"write")		\
+	EM(cachefiles_trace_write_nospace,	"write-nospace")	\
+	E_(cachefiles_trace_write_nospace_2,	"write-nospace-2")
 
 
 /*
@@ -694,6 +702,26 @@ TRACE_EVENT(cachefiles_io_error,
 		      __entry->error)
 	    );
 
+TRACE_EVENT(cachefiles_no_space,
+	    TP_PROTO(struct cachefiles_object *obj, enum cachefiles_error_trace trace),
+
+	    TP_ARGS(obj, trace),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,			obj)
+		    __field(enum cachefiles_error_trace,	trace)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->obj	= obj ? obj->debug_id : 0;
+		    __entry->trace	= trace;
+			   ),
+
+	    TP_printk("o=%08x %s",
+		      __entry->obj,
+		      __print_symbolic(__entry->trace, cachefiles_error_traces))
+	    );
+
 #endif /* _TRACE_CACHEFILES_H */
 
 /* This part must be outside protection */