ext4: fix initialization of UNINIT bitmap blocks

This fixes a bug which caused on-line resizing of filesystems with a
1k blocksize to fail.  The root cause of this bug was the fact that if
an uninitalized bitmap block gets read in by userspace (which
e2fsprogs does try to avoid, but can happen when the blocksize is less
than the pagesize and an adjacent blocks is read into memory)
ext4_read_block_bitmap() was erroneously depending on the buffer
uptodate flag to decide whether it needed to initialize the bitmap
block in memory --- i.e., to set the standard set of blocks in use by
a block group (superblock, bitmaps, inode table, etc.).  Essentially,
ext4_read_block_bitmap() assumed it was the only routine that might
try to read a block containing a block bitmap, which is simply not
true.

To fix this, ext4_read_block_bitmap() and ext4_read_inode_bitmap()
must always initialize uninitialized bitmap blocks.  Once a block or
inode is allocated out of that bitmap, it will be marked as
initialized in the block group descriptor, so in general this won't
result any extra unnecessary work.

Signed-off-by: Frederic Bohe <frederic.bohe@bull.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 59566c082f1b454aeabb862b5a52d7ee2ecc3f2c..bd2ece22882755b02599563a1bee89c5b10d2b87 100644 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -319,9 +319,11 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                return NULL;
        }
-       if (bh_uptodate_or_lock(bh))
+       if (buffer_uptodate(bh) &&
+           !(desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))
                return bh;
 
+       lock_buffer(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);

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 1343bf18825b0766744e5c3cdf0ba97ffc365e4f..fe34d74cfb19f89bd8435690511b54529982d984 100644 (file)
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -115,9 +115,11 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                return NULL;
        }
-       if (bh_uptodate_or_lock(bh))
+       if (buffer_uptodate(bh) &&
+           !(desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)))
                return bh;
 
+       lock_buffer(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);

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 335faee0c0f5ea898b896e584fa16e01859de68f..b580714f0d859c107e94a3f6c61286141fb0cdab 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -782,9 +782,11 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
                if (bh[i] == NULL)
                        goto out;
 
-               if (bh_uptodate_or_lock(bh[i]))
+               if (buffer_uptodate(bh[i]) &&
+                   !(desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))
                        continue;
 
+               lock_buffer(bh[i]);
                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],