ext4: make punch hole code path work with bigalloc

Currently punch hole is disabled in file systems with bigalloc
feature enabled. However the recent changes in punch hole patch should
make it easier to support punching holes on bigalloc enabled file
systems.

This commit changes partial_cluster handling in ext4_remove_blocks(),
ext4_ext_rm_leaf() and ext4_ext_remove_space(). Currently
partial_cluster is unsigned long long type and it makes sure that we
will free the partial cluster if all extents has been released from that
cluster. However it has been specifically designed only for truncate.

With punch hole we can be freeing just some extents in the cluster
leaving the rest untouched. So we have to make sure that we will notice
cluster which still has some extents. To do this I've changed
partial_cluster to be signed long long type. The only scenario where
this could be a problem is when cluster_size == block size, however in
that case there would not be any partial clusters so we're safe. For
bigger clusters the signed type is enough. Now we use the negative value
in partial_cluster to mark such cluster used, hence we know that we must
not free it even if all other extents has been freed from such cluster.

This scenario can be described in simple diagram:

|FFF...FF..FF.UUU|
 ^----------^
  punch hole

. - free space
| - cluster boundary
F - freed extent
U - used extent

Also update respective tracepoints to use signed long long type for
partial_cluster.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 13 insertions, 12 deletions

diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index bcb5a021945c..e23b2188110a 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -1928,7 +1928,7 @@ TRACE_EVENT(ext4_ext_show_extent,
 TRACE_EVENT(ext4_remove_blocks,
             TP_PROTO(struct inode *inode, struct ext4_extent *ex,
                 ext4_lblk_t from, ext4_fsblk_t to,
-                ext4_fsblk_t partial_cluster),
+                long long partial_cluster),
 
         TP_ARGS(inode, ex, from, to, partial_cluster),
 
@@ -1937,7 +1937,7 @@ TRACE_EVENT(ext4_remove_blocks,
                 __field(        ino_t,          ino     )
                 __field(        ext4_lblk_t,    from    )
                 __field(        ext4_lblk_t,    to      )
-                __field(        ext4_fsblk_t,   partial )
+                __field(        long long,      partial )
                 __field(        ext4_fsblk_t,   ee_pblk )
                 __field(        ext4_lblk_t,    ee_lblk )
                 __field(        unsigned short, ee_len  )
@@ -1955,7 +1955,7 @@ TRACE_EVENT(ext4_remove_blocks,
         ),
 
         TP_printk("dev %d,%d ino %lu extent [%u(%llu), %u]"
-                  "from %u to %u partial_cluster %u",
+                  "from %u to %u partial_cluster %lld",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   (unsigned long) __entry->ino,
                   (unsigned) __entry->ee_lblk,
@@ -1963,19 +1963,20 @@ TRACE_EVENT(ext4_remove_blocks,
                   (unsigned short) __entry->ee_len,
                   (unsigned) __entry->from,
                   (unsigned) __entry->to,
-                  (unsigned) __entry->partial)
+                  (long long) __entry->partial)
 );
 
 TRACE_EVENT(ext4_ext_rm_leaf,
         TP_PROTO(struct inode *inode, ext4_lblk_t start,
-                 struct ext4_extent *ex, ext4_fsblk_t partial_cluster),
+                 struct ext4_extent *ex,
+                 long long partial_cluster),
 
         TP_ARGS(inode, start, ex, partial_cluster),
 
         TP_STRUCT__entry(
                 __field(        dev_t,          dev     )
                 __field(        ino_t,          ino     )
-                __field(        ext4_fsblk_t,   partial )
+                __field(        long long,      partial )
                 __field(        ext4_lblk_t,    start   )
                 __field(        ext4_lblk_t,    ee_lblk )
                 __field(        ext4_fsblk_t,   ee_pblk )
@@ -1993,14 +1994,14 @@ TRACE_EVENT(ext4_ext_rm_leaf,
         ),
 
         TP_printk("dev %d,%d ino %lu start_lblk %u last_extent [%u(%llu), %u]"
-                  "partial_cluster %u",
+                  "partial_cluster %lld",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   (unsigned long) __entry->ino,
                   (unsigned) __entry->start,
                   (unsigned) __entry->ee_lblk,
                   (unsigned long long) __entry->ee_pblk,
                   (unsigned short) __entry->ee_len,
-                  (unsigned) __entry->partial)
+                  (long long) __entry->partial)
 );
 
 TRACE_EVENT(ext4_ext_rm_idx,
@@ -2058,7 +2059,7 @@ TRACE_EVENT(ext4_ext_remove_space,
 
 TRACE_EVENT(ext4_ext_remove_space_done,
         TP_PROTO(struct inode *inode, ext4_lblk_t start, ext4_lblk_t end,
-                 int depth, ext4_lblk_t partial, __le16 eh_entries),
+                 int depth, long long partial, __le16 eh_entries),
 
         TP_ARGS(inode, start, end, depth, partial, eh_entries),
 
@@ -2068,7 +2069,7 @@ TRACE_EVENT(ext4_ext_remove_space_done,
                 __field(        ext4_lblk_t,    start           )
                 __field(        ext4_lblk_t,    end             )
                 __field(        int,            depth           )
-                __field(        ext4_lblk_t,    partial         )
+                __field(        long long,      partial         )
                 __field(        unsigned short, eh_entries      )
         ),
 
@@ -2082,14 +2083,14 @@ TRACE_EVENT(ext4_ext_remove_space_done,
                 __entry->eh_entries     = le16_to_cpu(eh_entries);
         ),
 
-        TP_printk("dev %d,%d ino %lu since %u end %u depth %d partial %u "
+        TP_printk("dev %d,%d ino %lu since %u end %u depth %d partial %lld "
                   "remaining_entries %u",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   (unsigned long) __entry->ino,
                   (unsigned) __entry->start,
                   (unsigned) __entry->end,
                   __entry->depth,
-                  (unsigned) __entry->partial,
+                  (long long) __entry->partial,
                   (unsigned short) __entry->eh_entries)
 );