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List:       linux-ext4
Subject:    Re: [Ext2-devel] Problem freeing illegal preallocated block when
From:       Andrew Morton <akpm () digeo ! com>
Date:       2003-05-18 19:53:13
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Stuart Menefy <stuart.menefy@st.com> wrote:
> 
> This problem was seen in a 2.5.66 system, but appears to still be present
> in the current sources.
> 
> When trying to create a file on a newly mounted ext2 file system, which
> has no space remaining:
> 
> # touch wibble
> EXT2-fs error (device ramdisk(1,0)): ext2_free_blocks: Freeing blocks not in \
>                 datazone - block = 2147483648, count = 16
> touch: wibble: No space left on device
> 
> The problem is that ext2_discard_prealloc() is being called for a partly
> initialised inode, so picking up uninitialised values for i_prealloc_count:

Well found, and thanks for working through this.  But I believe it was
fixed in later kernels, by a different means:


From: "J. Bruce Fields" <bfields@fieldses.org>

If the NFS daemon is presented with a filehandle for a file that has
been deleted, it does an iget() in fs/exportfs/expfs.c:export_iget() and
gets a bad inode back.  When it subsequently iput()s the inode, the
result is:

Mar 27 12:53:40 snoopy kernel: EXT2-fs error (device ide0(3,3)): ext2_free_blocks: \
                Freeing blocks not in datazone - block = 1802201963, count = 27499
Mar 27 12:53:40 snoopy kernel: Remounting filesystem read-only

The same can happen if ext2_get_inode() returns an error - ext2_read_inode()
will return an uninitialised inode and ext2_put_inode() is not allowed to go
looking inside the bad inode.




 fs/ext2/inode.c |   11 ++++++++---
 fs/ext3/inode.c |    9 +++++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff -puN fs/ext2/inode.c~stale-inode-fix fs/ext2/inode.c
--- 25/fs/ext2/inode.c~stale-inode-fix	2003-04-02 22:50:46.000000000 -0800
+++ 25-akpm/fs/ext2/inode.c	2003-04-02 22:50:46.000000000 -0800
@@ -52,11 +52,16 @@ static inline int ext2_inode_is_fast_sym
 }
 
 /*
- * Called at each iput()
+ * Called at each iput().
+ *
+ * The inode may be "bad" if ext2_read_inode() saw an error from
+ * ext2_get_inode(), so we need to check that to avoid freeing random disk
+ * blocks.
  */
-void ext2_put_inode (struct inode * inode)
+void ext2_put_inode(struct inode *inode)
 {
-	ext2_discard_prealloc (inode);
+	if (!is_bad_inode(inode))
+		ext2_discard_prealloc(inode);
 }
 
 /*
diff -puN fs/ext3/inode.c~stale-inode-fix fs/ext3/inode.c
--- 25/fs/ext3/inode.c~stale-inode-fix	2003-04-02 22:50:46.000000000 -0800
+++ 25-akpm/fs/ext3/inode.c	2003-04-02 22:50:46.000000000 -0800
@@ -178,10 +178,15 @@ static int ext3_journal_test_restart(han
 
 /*
  * Called at each iput()
+ *
+ * The inode may be "bad" if ext3_read_inode() saw an error from
+ * ext3_get_inode(), so we need to check that to avoid freeing random disk
+ * blocks.
  */
-void ext3_put_inode (struct inode * inode)
+void ext3_put_inode(struct inode *inode)
 {
-	ext3_discard_prealloc (inode);
+	if (!is_bad_inode(inode))
+		ext3_discard_prealloc(inode);
 }
 
 /*

_



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