Commit fc82228a authored Dec 03, 2017 by Andi Kleen Committed by Theodore Ts'o Dec 03, 2017

ext4: support fast symlinks from ext3 file systems



407cd7fb (ext4: change fast symlink test to not rely on i_blocks)
broke ~10 years old ext3 file systems created by 2.6.17. Any ELF
executable fails because the /lib/ld-linux.so.2 fast symlink
cannot be read anymore.

The patch assumed fast symlinks were created in a specific way,
but that's not true on these really old file systems.

The new behavior is apparently needed only with the large EA inode
feature.

Revert to the old behavior if the large EA inode feature is not set.

This makes my old VM boot again.

Fixes: 407cd7fb (ext4: change fast symlink test to not rely on i_blocks)
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: stable@vger.kernel.org

parent ae64f9bd

fs/ext4/inode.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -149,6 +149,15 @@ static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
		*/
		int ext4_inode_is_fast_symlink(struct inode *inode)
		{
		if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
		int ea_blocks = EXT4_I(inode)->i_file_acl ?
		EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;

		if (ext4_has_inline_data(inode))
		return 0;

		return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
		}
		return S_ISLNK(inode->i_mode) && inode->i_size &&
		(inode->i_size < EXT4_N_BLOCKS * 4);
		}

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