Fix: writeback probe on RHEL >= 3.10.0-327.10.1

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/instrumentation/events/lttng-module/writeback.h b/instrumentation/events/lttng-module/writeback.h
index 215662b783887d1d05cc7b5adb40cebce7d53ba6..5f65cdc70247fa1fed8f0a7fcc9b4dd18fc36fd0 100644 (file)
--- a/instrumentation/events/lttng-module/writeback.h
+++ b/instrumentation/events/lttng-module/writeback.h
@@ -13,17 +13,34 @@
 #ifndef _TRACE_WRITEBACK_DEF_
 #define _TRACE_WRITEBACK_DEF_
 
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,0,0) && \
-       LTTNG_RHEL_VERSION_CODE < LTTNG_RHEL_KERNEL_VERSION(3,10,0,327,10,1))
-static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
+/*
+ * Vanilla kernels before 4.0 do not implement inode_to_bdi
+ * RHEL kernels before 3.10.0-327.10.1 do not implement inode_to_bdi
+ * RHEL kernel 3.10.0-327.10.1 has inode_to_bdi
+ * RHEL kernel 3.10.0-327.13.1 includes a partial merge of upstream
+ *  commit a212b105b07d75b48b1a166378282e8a77fbf53d which inlines
+ *  inode_to_bdi but not sb_is_blkdev_sb making it unusable by modules.
+ */
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,0,0))
+static inline struct backing_dev_info *lttng_inode_to_bdi(struct inode *inode)
 {
-       struct super_block *sb = inode->i_sb;
+       struct super_block *sb;
+
+       if (!inode)
+               return &noop_backing_dev_info;
+
+       sb = inode->i_sb;
 
        if (strcmp(sb->s_type->name, "bdev") == 0)
                return inode->i_mapping->backing_dev_info;
 
        return sb->s_bdi;
 }
+#else
+static inline struct backing_dev_info *lttng_inode_to_bdi(struct inode *inode)
+{
+       return inode_to_bdi(inode);
+}
 #endif /* #if (LINUX_VERSION_CODE < KERNEL_VERSION(4,0,0)) */
 
 #endif
@@ -65,7 +82,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_dirty_page,
        TP_ARGS(page, mapping),
        TP_FIELDS(
                ctf_array_text(char, name,
-                       mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32)
+                       mapping ? dev_name(lttng_inode_to_bdi(mapping->host)->dev) : "(unknown)", 32)
                ctf_integer(unsigned long, ino, mapping ? mapping->host->i_ino : 0)
                ctf_integer(pgoff_t, index, page->index)
        )
@@ -77,8 +94,8 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_dirty_inode_template,
        TP_FIELDS(
                /* may be called for files on pseudo FSes w/ unregistered bdi */
                ctf_array_text(char, name,
-                       inode_to_bdi(inode)->dev ?
-                               dev_name(inode_to_bdi(inode)->dev) : "(unknown)", 32)
+                       lttng_inode_to_bdi(inode)->dev ?
+                               dev_name(lttng_inode_to_bdi(inode)->dev) : "(unknown)", 32)
                ctf_integer(unsigned long, ino, inode->i_ino)
                ctf_integer(unsigned long, state, inode->i_state)
                ctf_integer(unsigned long, flags, flags)
@@ -97,7 +114,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_write_inode_template,
        TP_ARGS(inode, wbc),
        TP_FIELDS(
                ctf_array_text(char, name,
-                       dev_name(inode_to_bdi(inode)->dev), 32)
+                       dev_name(lttng_inode_to_bdi(inode)->dev), 32)
                ctf_integer(unsigned long, ino, inode->i_ino)
                ctf_integer(int, sync_mode, wbc->sync_mode)
        )
@@ -609,7 +626,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_sb_inodes_requeue,
 
        TP_FIELDS(
                ctf_array_text(char, name,
-                       dev_name(inode_to_bdi(inode)->dev), 32)
+                       dev_name(lttng_inode_to_bdi(inode)->dev), 32)
                ctf_integer(unsigned long, ino, inode->i_ino)
                ctf_integer(unsigned long, state, inode->i_state)
                ctf_integer(unsigned long, dirtied_when, inode->dirtied_when)
@@ -657,7 +674,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_single_inode_template,
 
        TP_FIELDS(
                ctf_array_text(char, name,
-                       dev_name(inode_to_bdi(inode)->dev), 32)
+                       dev_name(lttng_inode_to_bdi(inode)->dev), 32)
                ctf_integer(unsigned long, ino, inode->i_ino)
                ctf_integer(unsigned long, state, inode->i_state)
                ctf_integer(unsigned long, dirtied_when, inode->dirtied_when)