ext4: fix unjournalled bg descriptor while initializing inode bitmap (61c219f5) · Commits · 戴 / test

The first time that we allocate from an uninitialized inode allocation bitmap, if the block allocation bitmap is also uninitalized, we need to get write access to the block group descriptor before we start modifying the block group descriptor flags and updating the free block count, etc. Otherwise, there is the potential of a bad journal checksum (if journal checksums are enabled), and of the file system becoming inconsistent if we crash at exactly the wrong time. Signed-off-by:

Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org

fs/ext4/ialloc.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -874,6 +874,13 @@ got:
		goto out;
		}

		BUFFER_TRACE(group_desc_bh, "get_write_access");
		err = ext4_journal_get_write_access(handle, group_desc_bh);
		if (err) {
		ext4_std_error(sb, err);
		goto out;
		}

		/* We may have to initialize the block bitmap if it isn't already */
		if (ext4_has_group_desc_csum(sb) &&
		gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
		@@ -910,13 +917,6 @@ got:
		}
		}

		BUFFER_TRACE(group_desc_bh, "get_write_access");
		err = ext4_journal_get_write_access(handle, group_desc_bh);
		if (err) {
		ext4_std_error(sb, err);
		goto out;
		}

		/* Update the relevant bg descriptor fields */
		if (ext4_has_group_desc_csum(sb)) {
		int free;

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