[lttng-dev] [PATCH lttng-modules v2] Fix: writeback probe on RHEL >= 3.10.0-327.10.1

[mathieu.desnoyers@efficios.com (Mathieu Desnoyers)]

Merged into master, 2.7 and 2.8, thanks!

Mathieu

----- On Apr 21, 2016, at 4:11 PM, Michael Jeanson mjeanson at efficios.com wrote:

> Signed-off-by: Michael Jeanson <mjeanson at efficios.com>
> ---
> instrumentation/events/lttng-module/writeback.h | 37 ++++++++++++++++++-------
> 1 file changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/instrumentation/events/lttng-module/writeback.h
> b/instrumentation/events/lttng-module/writeback.h
> index a215f55..6006c29 100644
> --- 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)
> --
> 2.7.4

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com