ext4: Use new buffer_head flag to check uninit group bitmaps initialization

For uninit block group, the on-disk bitmap is not initialized. That
implies we cannot depend on the uptodate flag on the bitmap
buffer_head to find bitmap validity.  Use a new buffer_head flag which
would be set after we properly initialize the bitmap.  This also
prevents (re-)initializing the uninit group bitmap every time we call
ext4_read_block_bitmap().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 1b26b68..6bba06b 100644 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -320,20 +320,41 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                return NULL;
        }
-       if (buffer_uptodate(bh) &&
-           !(desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))
+
+       if (bitmap_uptodate(bh))
                return bh;
 
        lock_buffer(bh);
+       if (bitmap_uptodate(bh)) {
+               unlock_buffer(bh);
+               return bh;
+       }
        spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                ext4_init_block_bitmap(sb, bh, block_group, desc);
+               set_bitmap_uptodate(bh);
                set_buffer_uptodate(bh);
                spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
                unlock_buffer(bh);
                return bh;
        }
        spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+       if (buffer_uptodate(bh)) {
+               /*
+                * if not uninit if bh is uptodate,
+                * bitmap is also uptodate
+                */
+               set_bitmap_uptodate(bh);
+               unlock_buffer(bh);
+               return bh;
+       }
+       /*
+        * submit the buffer_head for read. We can
+        * safely mark the bitmap as uptodate now.
+        * We do it here so the bitmap uptodate bit
+        * get set with buffer lock held.
+        */
+       set_bitmap_uptodate(bh);
        if (bh_submit_read(bh) < 0) {
                put_bh(bh);
                ext4_error(sb, __func__,

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ec862f4..695b45c 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -19,6 +19,7 @@
 #include <linux/types.h>
 #include <linux/blkdev.h>
 #include <linux/magic.h>
+#include <linux/jbd2.h>
 #include "ext4_i.h"
 
 /*
@@ -1352,6 +1353,23 @@ extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
 extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                        __u64 start, __u64 len);
 
+/*
+ * Add new method to test wether block and inode bitmaps are properly
+ * initialized. With uninit_bg reading the block from disk is not enough
+ * to mark the bitmap uptodate. We need to also zero-out the bitmap
+ */
+#define BH_BITMAP_UPTODATE BH_JBDPrivateStart
+
+static inline int bitmap_uptodate(struct buffer_head *bh)
+{
+       return (buffer_uptodate(bh) &&
+                       test_bit(BH_BITMAP_UPTODATE, &(bh)->b_state));
+}
+static inline void set_bitmap_uptodate(struct buffer_head *bh)
+{
+       set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _EXT4_H */

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index d4e544f..7b12aed 100644 (file)
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -115,20 +115,40 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                return NULL;
        }
-       if (buffer_uptodate(bh) &&
-           !(desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)))
+       if (bitmap_uptodate(bh))
                return bh;
 
        lock_buffer(bh);
+       if (bitmap_uptodate(bh)) {
+               unlock_buffer(bh);
+               return bh;
+       }
        spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
                ext4_init_inode_bitmap(sb, bh, block_group, desc);
+               set_bitmap_uptodate(bh);
                set_buffer_uptodate(bh);
                spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
                unlock_buffer(bh);
                return bh;
        }
        spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+       if (buffer_uptodate(bh)) {
+               /*
+                * if not uninit if bh is uptodate,
+                * bitmap is also uptodate
+                */
+               set_bitmap_uptodate(bh);
+               unlock_buffer(bh);
+               return bh;
+       }
+       /*
+        * submit the buffer_head for read. We can
+        * safely mark the bitmap as uptodate now.
+        * We do it here so the bitmap uptodate bit
+        * get set with buffer lock held.
+        */
+       set_bitmap_uptodate(bh);
        if (bh_submit_read(bh) < 0) {
                put_bh(bh);
                ext4_error(sb, __func__,

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index aac3359..18a52d3 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -794,22 +794,42 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
                if (bh[i] == NULL)
                        goto out;
 
-               if (buffer_uptodate(bh[i]) &&
-                   !(desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))
+               if (bitmap_uptodate(bh[i]))
                        continue;
 
                lock_buffer(bh[i]);
+               if (bitmap_uptodate(bh[i])) {
+                       unlock_buffer(bh[i]);
+                       continue;
+               }
                spin_lock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
                if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                        ext4_init_block_bitmap(sb, bh[i],
                                                first_group + i, desc);
+                       set_bitmap_uptodate(bh[i]);
                        set_buffer_uptodate(bh[i]);
                        spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
                        unlock_buffer(bh[i]);
                        continue;
                }
                spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
+               if (buffer_uptodate(bh[i])) {
+                       /*
+                        * if not uninit if bh is uptodate,
+                        * bitmap is also uptodate
+                        */
+                       set_bitmap_uptodate(bh[i]);
+                       unlock_buffer(bh[i]);
+                       continue;
+               }
                get_bh(bh[i]);
+               /*
+                * submit the buffer_head for read. We can
+                * safely mark the bitmap as uptodate now.
+                * We do it here so the bitmap uptodate bit
+                * get set with buffer lock held.
+                */
+               set_bitmap_uptodate(bh[i]);
                bh[i]->b_end_io = end_buffer_read_sync;
                submit_bh(READ, bh[i]);
                mb_debug("read bitmap for group %u\n", first_group + i);