releases/2.6.32.1/0022-ext4-Avoid-data-filesystem-corruption-when-write-fai.patch

   1 From 968c53cec156cb9a3239969a3686c33a0e5cc9ab Mon Sep 17 00:00:00 2001
   2 From: Jan Kara <jack@suse.cz>
   3 Date: Tue, 8 Dec 2009 21:24:33 -0500
   4 Subject: [PATCH 22/30] ext4: Avoid data / filesystem corruption when write fails to copy data
   5
   6 (cherry picked from commit b9a4207d5e911b938f73079a83cc2ae10524ec7f)
   7
   8 When ext4_write_begin fails after allocating some blocks or
   9 generic_perform_write fails to copy data to write, we truncate blocks
  10 already instantiated beyond i_size.  Although these blocks were never
  11 inside i_size, we have to truncate the pagecache of these blocks so
  12 that corresponding buffers get unmapped.  Otherwise subsequent
  13 __block_prepare_write (called because we are retrying the write) will
  14 find the buffers mapped, not call ->get_block, and thus the page will
  15 be backed by already freed blocks leading to filesystem and data
  16 corruption.
  17
  18 Signed-off-by: Jan Kara <jack@suse.cz>
  19 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  21 ---
  22  fs/ext4/inode.c |   20 +++++++++++++++-----
  23  1 file changed, 15 insertions(+), 5 deletions(-)
  24
  25 --- a/fs/ext4/inode.c
  26 +++ b/fs/ext4/inode.c
  27 @@ -1534,6 +1534,16 @@ static int do_journal_get_write_access(h
  28         return ext4_journal_get_write_access(handle, bh);
  29  }
  30
  31 +/*
  32 + * Truncate blocks that were not used by write. We have to truncate the
  33 + * pagecache as well so that corresponding buffers get properly unmapped.
  34 + */
  35 +static void ext4_truncate_failed_write(struct inode *inode)
  36 +{
  37 +       truncate_inode_pages(inode->i_mapping, inode->i_size);
  38 +       ext4_truncate(inode);
  39 +}
  40 +
  41  static int ext4_write_begin(struct file *file, struct address_space *mapping,
  42                             loff_t pos, unsigned len, unsigned flags,
  43                             struct page **pagep, void **fsdata)
  44 @@ -1599,7 +1609,7 @@ retry:
  45
  46                 ext4_journal_stop(handle);
  47                 if (pos + len > inode->i_size) {
  48 -                       ext4_truncate(inode);
  49 +                       ext4_truncate_failed_write(inode);
  50                         /*
  51                          * If truncate failed early the inode might
  52                          * still be on the orphan list; we need to
  53 @@ -1709,7 +1719,7 @@ static int ext4_ordered_write_end(struct
  54                 ret = ret2;
  55
  56         if (pos + len > inode->i_size) {
  57 -               ext4_truncate(inode);
  58 +               ext4_truncate_failed_write(inode);
  59                 /*
  60                  * If truncate failed early the inode might still be
  61                  * on the orphan list; we need to make sure the inode
  62 @@ -1751,7 +1761,7 @@ static int ext4_writeback_write_end(stru
  63                 ret = ret2;
  64
  65         if (pos + len > inode->i_size) {
  66 -               ext4_truncate(inode);
  67 +               ext4_truncate_failed_write(inode);
  68                 /*
  69                  * If truncate failed early the inode might still be
  70                  * on the orphan list; we need to make sure the inode
  71 @@ -1814,7 +1824,7 @@ static int ext4_journalled_write_end(str
  72         if (!ret)
  73                 ret = ret2;
  74         if (pos + len > inode->i_size) {
  75 -               ext4_truncate(inode);
  76 +               ext4_truncate_failed_write(inode);
  77                 /*
  78                  * If truncate failed early the inode might still be
  79                  * on the orphan list; we need to make sure the inode
  80 @@ -3091,7 +3101,7 @@ retry:
  81                  * i_size_read because we hold i_mutex.
  82                  */
  83                 if (pos + len > inode->i_size)
  84 -                       ext4_truncate(inode);
  85 +                       ext4_truncate_failed_write(inode);
  86         }
  87
  88         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))