btrfs: Rename EXTENT_BUFFER_DUMMY to EXTENT_BUFFER_UNMAPPED

EXTENT_BUFFER_DUMMY is an awful name for this flag. Buffers which have
this flag set are not in any way dummy. Rather, they are private in the
sense that are not mapped and linked to the global buffer tree. This
flag has subtle implications to the way free_extent_buffer works for
example, as well as controls whether page->mapping->private_lock is held
during extent_buffer release. Pages for an unmapped buffer cannot be
under io, nor can they be written by a 3rd party so taking the lock is
unnecessary.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ EXTENT_BUFFER_UNMAPPED, update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e3858b2fe014833c080b95236bf063b456e53140..a4b713d03a33241dda15c737e1acc4f650376e97 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4089,10 +4089,10 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
        /*
         * This is a fast path so only do this check if we have sanity tests
-        * enabled.  Normal people shouldn't be marking dummy buffers as dirty
+        * enabled.  Normal people shouldn't be using umapped buffers as dirty
         * outside of the sanity tests.
         */
-       if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &buf->bflags)))
+       if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &buf->bflags)))
                return;
 #endif
        root = BTRFS_I(buf->pages[0]->mapping->host)->root;

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5ab401f79683896865474a4ffd0ea768b1263255..3440053f3599231c185d4186ef8a9410d09eb85b 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4649,7 +4649,7 @@ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb)
 {
        int i;
        int num_pages;
-       int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
+       int mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
 
        BUG_ON(extent_buffer_under_io(eb));
 
@@ -4763,7 +4763,7 @@ struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
        }
 
        set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
-       set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
+       set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
 
        return new;
 }
@@ -4787,7 +4787,7 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
        }
        set_extent_buffer_uptodate(eb);
        btrfs_set_header_nritems(eb, 0);
-       set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
+       set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
 
        return eb;
 err:
@@ -5088,7 +5088,7 @@ static int release_extent_buffer(struct extent_buffer *eb)
                /* Should be safe to release our pages at this point */
                btrfs_release_extent_buffer_pages(eb);
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-               if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
+               if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) {
                        __free_extent_buffer(eb);
                        return 1;
                }
@@ -5119,7 +5119,7 @@ void free_extent_buffer(struct extent_buffer *eb)
 
        spin_lock(&eb->refs_lock);
        if (atomic_read(&eb->refs) == 2 &&
-           test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
+           test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))
                atomic_dec(&eb->refs);
 
        if (atomic_read(&eb->refs) == 2 &&

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 48f1ee9ad3793766807ed657fffdf7f3a011144b..0ecc13b7d6f7d968c26e31e45f18afbdaeda481f 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -46,7 +46,7 @@
 #define EXTENT_BUFFER_STALE 6
 #define EXTENT_BUFFER_WRITEBACK 7
 #define EXTENT_BUFFER_READ_ERR 8        /* read IO error */
-#define EXTENT_BUFFER_DUMMY 9
+#define EXTENT_BUFFER_UNMAPPED 9
 #define EXTENT_BUFFER_IN_TREE 10
 #define EXTENT_BUFFER_WRITE_ERR 11    /* write IO error */