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

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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
This commit is contained in:
Aneesh Kumar K.V
2009-01-05 21:49:55 -05:00
committed by Theodore Ts'o
parent 393418676a
commit 2ccb5fb9f1
4 changed files with 85 additions and 6 deletions
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24
fs/ext4/mballoc.c
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@@ -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);