ext4: fix error handling in ext4_ext_truncate()

Previously ext4_ext_truncate() was ignoring potential error returns
from ext4_es_remove_extent() and ext4_ext_remove_space().  This can
lead to the on-diks extent tree and the extent status tree cache
getting out of sync, which is particuarlly bad, and can lead to file
system corruption and potential data loss.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7097b0f680e62bbf674364008ef66887a5e0fdca..f57cc0e7f1bca35cbd45278f26eff4a699307430 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4405,9 +4405,20 @@ void ext4_ext_truncate(handle_t *handle, struct inode *inode)
 
        last_block = (inode->i_size + sb->s_blocksize - 1)
                        >> EXT4_BLOCK_SIZE_BITS(sb);
+retry:
        err = ext4_es_remove_extent(inode, last_block,
                                    EXT_MAX_BLOCKS - last_block);
+       if (err == ENOMEM) {
+               cond_resched();
+               congestion_wait(BLK_RW_ASYNC, HZ/50);
+               goto retry;
+       }
+       if (err) {
+               ext4_std_error(inode->i_sb, err);
+               return;
+       }
        err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
+       ext4_std_error(inode->i_sb, err);
 }
 
 static void ext4_falloc_update_inode(struct inode *inode,