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Commit | Line | Data |
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2cb7cef9 BS |
1 | From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
2 | Date: Thu, 14 May 2009 21:05:39 +0000 (-0400) | |
3 | Subject: ext4: Clear the unwritten buffer_head flag after the extent is initialized | |
4 | Patch-mainline: 2.6.30-rc6 | |
5 | Git-commit: 2a8964d63d50dd2d65d71d342bc7fb6ef4117614 | |
6 | References: bnc#503161 | |
7 | ||
8 | ext4: Clear the unwritten buffer_head flag after the extent is initialized | |
9 | ||
10 | The BH_Unwritten flag indicates that the buffer is allocated on disk | |
11 | but has not been written; that is, the disk was part of a persistent | |
12 | preallocation area. That flag should only be set when a get_blocks() | |
13 | function is looking up a inode's logical to physical block mapping. | |
14 | ||
15 | When ext4_get_blocks_wrap() is called with create=1, the uninitialized | |
16 | extent is converted into an initialized one, so the BH_Unwritten flag | |
17 | is no longer appropriate. Hence, we need to make sure the | |
18 | BH_Unwritten is not left set, since the combination of BH_Mapped and | |
19 | BH_Unwritten is not allowed; among other things, it will result ext4's | |
20 | get_block() to be called over and over again during the write_begin | |
21 | phase of write(2). | |
22 | ||
23 | Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | |
24 | Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> | |
25 | Acked-by: Jeff Mahoney <jeffm@suse.com> | |
26 | --- | |
27 | ||
28 | fs/ext4/inode.c | 13 +++++++++++++ | |
29 | 1 file changed, 13 insertions(+) | |
30 | ||
31 | --- a/fs/ext4/inode.c | |
32 | +++ b/fs/ext4/inode.c | |
33 | @@ -1058,6 +1058,7 @@ int ext4_get_blocks_wrap(handle_t *handl | |
34 | int retval; | |
35 | ||
36 | clear_buffer_mapped(bh); | |
37 | + clear_buffer_unwritten(bh); | |
38 | ||
39 | /* | |
40 | * Try to see if we can get the block without requesting | |
41 | @@ -1088,6 +1089,18 @@ int ext4_get_blocks_wrap(handle_t *handl | |
42 | return retval; | |
43 | ||
44 | /* | |
45 | + * When we call get_blocks without the create flag, the | |
46 | + * BH_Unwritten flag could have gotten set if the blocks | |
47 | + * requested were part of a uninitialized extent. We need to | |
48 | + * clear this flag now that we are committed to convert all or | |
49 | + * part of the uninitialized extent to be an initialized | |
50 | + * extent. This is because we need to avoid the combination | |
51 | + * of BH_Unwritten and BH_Mapped flags being simultaneously | |
52 | + * set on the buffer_head. | |
53 | + */ | |
54 | + clear_buffer_unwritten(bh); | |
55 | + | |
56 | + /* | |
57 | * New blocks allocate and/or writing to uninitialized extent | |
58 | * will possibly result in updating i_data, so we take | |
59 | * the write lock of i_data_sem, and call get_blocks() |