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authorHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>2008-07-26 16:39:26 -0400
committerTheodore Ts'o <tytso@mit.edu>2008-07-26 16:39:26 -0400
commit9c83a923c67df311c467ec956009f0eb4019195d (patch)
treefbe6cbcfae2406ebbd842859ae445aa6f59276b6 /fs/ext4
parent6be2ded1d7c51b39144b9f07d2c839e1bd8707f1 (diff)
ext4: don't read inode block if the buffer has a write error
A transient I/O error can corrupt inode data. Here is the scenario: (1) update inode_A at the block_B (2) pdflush writes out new inode_A to the filesystem, but it results in write I/O error, at this point, BH_Uptodate flag of the buffer for block_B is cleared and BH_Write_EIO is set (3) create new inode_C which located at block_B, and __ext4_get_inode_loc() tries to read on-disk block_B because the buffer is not uptodate (4) if it can read on-disk block_B successfully, inode_A is overwritten by old data This patch makes __ext4_get_inode_loc() not read the inode block if the buffer has BH_Write_EIO flag. In this case, the buffer should have the latest information, so setting the uptodate flag to the buffer (this avoids WARN_ON_ONCE() in mark_buffer_dirty().) According to this change, we would need to test BH_Write_EIO flag for the error checking. Currently nobody checks write I/O errors on metadata buffers, but it will be done in other patches I'm working on. Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Cc: sugita <yumiko.sugita.yf@hitachi.com> Cc: Satoshi OSHIMA <satoshi.oshima.fk@hitachi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Jan Kara <jack@ucw.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9843b046c23..efe8caa3811 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3590,6 +3590,16 @@ static int __ext4_get_inode_loc(struct inode *inode,
}
if (!buffer_uptodate(bh)) {
lock_buffer(bh);
+
+ /*
+ * If the buffer has the write error flag, we have failed
+ * to write out another inode in the same block. In this
+ * case, we don't have to read the block because we may
+ * read the old inode data successfully.
+ */
+ if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
+ set_buffer_uptodate(bh);
+
if (buffer_uptodate(bh)) {
/* someone brought it uptodate while we waited */
unlock_buffer(bh);