[PATCH 27/67] cachefiles: trace: Log coherency checks

David Howells
2021-10-18T14:57:59Z

Add a cachefiles tracepoint that logs the result of coherency management
when the coherency data on a file in the cache is checked or committed.

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

fs/cachefiles/xattr.c | 44 +++++++++++++++++++++--------
include/trace/events/cachefiles.h | 56 +++++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 12 deletions(-)

diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index 2f14618d9a36..bfb2f4d605af 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c
@@ -53,12 +53,21 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object,
ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache,
buf, sizeof(struct cachefiles_xattr) + len,
xattr_flags);
- kfree(buf);
- if (ret < 0 && ret != -ENOMEM)
- cachefiles_io_error_obj(
- object,
- "Failed to set xattr with error %d", ret);
+ if (ret < 0) {
+ trace_cachefiles_coherency(object, file_inode(file)->i_ino,
+ 0,
+ cachefiles_coherency_set_fail);
+ if (ret != -ENOMEM)
+ cachefiles_io_error_obj(
+ object,
+ "Failed to set xattr with error %d", ret);
+ } else {
+ trace_cachefiles_coherency(object, file_inode(file)->i_ino,
+ 0,
+ cachefiles_coherency_set_ok);
+ }

+ kfree(buf);
_leave(" = %d", ret);
return ret;
}
@@ -72,21 +81,32 @@ int cachefiles_check_auxdata(struct cachefiles_object *object)
struct dentry *dentry = object->file->f_path.dentry;
unsigned int len = object->cookie->aux_len, tlen;
const void *p = fscache_get_aux(object->cookie);
- ssize_t ret;
+ enum cachefiles_coherency_trace why;
+ ssize_t xlen;
+ int ret = -ESTALE;

tlen = sizeof(struct cachefiles_xattr) + len;
buf = kmalloc(tlen, GFP_KERNEL);
if (!buf)
return -ENOMEM;

- ret = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, tlen);
- if (ret == tlen &&
- buf->type == object->cookie->type &&
- memcmp(buf->data, p, len) == 0)
+ xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, tlen);
+ if (xlen != tlen) {
+ if (xlen == -EIO)
+ cachefiles_io_error_obj(
+ object,
+ "Failed to read aux with error %zd", xlen);
+ why = cachefiles_coherency_check_xattr;
+ } else if (buf->type != object->cookie->type) {
+ why = cachefiles_coherency_check_type;
+ } else if (memcmp(buf->data, p, len) != 0) {
+ why = cachefiles_coherency_check_aux;
+ } else {
+ why = cachefiles_coherency_check_ok;
ret = 0;
- else
- ret = -ESTALE;
+ }

+ trace_cachefiles_coherency(object, file_inode(object->file)->i_ino, 0, why);
kfree(buf);
return ret;
}
diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h
index 10ad5305d1c5..6e9f6462833d 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -24,6 +24,19 @@ enum cachefiles_obj_ref_trace {
cachefiles_obj_ref__nr_traces
};

+enum cachefiles_coherency_trace {
+ cachefiles_coherency_check_aux,
+ cachefiles_coherency_check_content,
+ cachefiles_coherency_check_dirty,
+ cachefiles_coherency_check_len,
+ cachefiles_coherency_check_objsize,
+ cachefiles_coherency_check_ok,
+ cachefiles_coherency_check_type,
+ cachefiles_coherency_check_xattr,
+ cachefiles_coherency_set_fail,
+ cachefiles_coherency_set_ok,
+};
+
#endif

/*
@@ -47,6 +60,18 @@ enum cachefiles_obj_ref_trace {
EM(cachefiles_obj_put_wait_retry, "PUT wait_retry") \
E_(cachefiles_obj_put_wait_timeo, "PUT wait_timeo")

+#define cachefiles_coherency_traces \
+ EM(cachefiles_coherency_check_aux, "BAD aux ") \
+ EM(cachefiles_coherency_check_content, "BAD cont") \
+ EM(cachefiles_coherency_check_dirty, "BAD dirt") \
+ EM(cachefiles_coherency_check_len, "BAD len ") \
+ EM(cachefiles_coherency_check_objsize, "BAD osiz") \
+ EM(cachefiles_coherency_check_ok, "OK ") \
+ EM(cachefiles_coherency_check_type, "BAD type") \
+ EM(cachefiles_coherency_check_xattr, "BAD xatt") \
+ EM(cachefiles_coherency_set_fail, "SET fail") \
+ E_(cachefiles_coherency_set_ok, "SET ok ")
+
/*
* Export enum symbols via userspace.
*/
@@ -57,6 +82,7 @@ enum cachefiles_obj_ref_trace {

cachefiles_obj_kill_traces;
cachefiles_obj_ref_traces;
+cachefiles_coherency_traces;

/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -236,6 +262,36 @@ TRACE_EVENT(cachefiles_mark_inactive,
__entry->obj, __entry->inode)
);

+TRACE_EVENT(cachefiles_coherency,
+ TP_PROTO(struct cachefiles_object *obj,
+ ino_t ino,
+ int content,
+ enum cachefiles_coherency_trace why),
+
+ TP_ARGS(obj, ino, content, why),
+
+ /* Note that obj may be NULL */
+ TP_STRUCT__entry(
+ __field(unsigned int, obj )
+ __field(enum cachefiles_coherency_trace, why )
+ __field(int, content )
+ __field(u64, ino )
+ ),
+
+ TP_fast_assign(
+ __entry->obj = obj->debug_id;
+ __entry->why = why;
+ __entry->content = content;
+ __entry->ino = ino;
+ ),
+
+ TP_printk("o=%08x %s i=%llx c=%u",
+ __entry->obj,
+ __print_symbolic(__entry->why, cachefiles_coherency_traces),
+ __entry->ino,
+ __entry->content)
+ );
+
#endif /* _TRACE_CACHEFILES_H */

/* This part must be outside protection */