From d03856bd5e5abac717da137dc60fe4a691769bd0 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Sat, 2 Aug 2008 18:51:32 -0400 Subject: [PATCH] ext4: Fix data corruption when writing to prealloc area Inserting an extent can cause a new entry in the already existing index block. That doesn't increase the depth of the instead. Instead it adds a new leaf block. Now with the new leaf block the path information corresponding to the logical block should be fetched from the new block. The old path will be pointing to the old leaf block. We need to recalucate the path information on extent insert even if depth doesn't change. Without this change, the extent merge after converting an unwritten extent to initialized extent takes the wrong extent and cause data corruption. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Mingming Cao Signed-off-by: "Theodore Ts'o" --- fs/ext4/extents.c | 41 +++++++++++++++++++++++------------------ 1 file changed, 23 insertions(+), 18 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 42c4c0c892e..8ee1fa54a4e 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2323,7 +2323,10 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, unsigned int newdepth; /* If extent has less than EXT4_EXT_ZERO_LEN zerout directly */ if (allocated <= EXT4_EXT_ZERO_LEN) { - /* Mark first half uninitialized. + /* + * iblock == ee_block is handled by the zerouout + * at the beginning. + * Mark first half uninitialized. * Mark second half initialized and zero out the * initialized extent */ @@ -2346,7 +2349,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, ex->ee_len = orig_ex.ee_len; ext4_ext_store_pblock(ex, ext_pblock(&orig_ex)); ext4_ext_dirty(handle, inode, path + depth); - /* zeroed the full extent */ + /* blocks available from iblock */ return allocated; } else if (err) @@ -2374,6 +2377,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, err = PTR_ERR(path); return err; } + /* get the second half extent details */ ex = path[depth].p_ext; err = ext4_ext_get_access(handle, inode, path + depth); @@ -2403,6 +2407,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, ext4_ext_store_pblock(ex, ext_pblock(&orig_ex)); ext4_ext_dirty(handle, inode, path + depth); /* zeroed the full extent */ + /* blocks available from iblock */ return allocated; } else if (err) @@ -2418,23 +2423,22 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, */ orig_ex.ee_len = cpu_to_le16(ee_len - ext4_ext_get_actual_len(ex3)); - if (newdepth != depth) { - depth = newdepth; - ext4_ext_drop_refs(path); - path = ext4_ext_find_extent(inode, iblock, path); - if (IS_ERR(path)) { - err = PTR_ERR(path); - goto out; - } - eh = path[depth].p_hdr; - ex = path[depth].p_ext; - if (ex2 != &newex) - ex2 = ex; - - err = ext4_ext_get_access(handle, inode, path + depth); - if (err) - goto out; + depth = newdepth; + ext4_ext_drop_refs(path); + path = ext4_ext_find_extent(inode, iblock, path); + if (IS_ERR(path)) { + err = PTR_ERR(path); + goto out; } + eh = path[depth].p_hdr; + ex = path[depth].p_ext; + if (ex2 != &newex) + ex2 = ex; + + err = ext4_ext_get_access(handle, inode, path + depth); + if (err) + goto out; + allocated = max_blocks; /* If extent has less than EXT4_EXT_ZERO_LEN and we are trying @@ -2452,6 +2456,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, ext4_ext_store_pblock(ex, ext_pblock(&orig_ex)); ext4_ext_dirty(handle, inode, path + depth); /* zero out the first half */ + /* blocks available from iblock */ return allocated; } } -- 2.41.1