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| author | Dmitry Monakhov <dmonakhov@openvz.org> | 2012-09-29 00:55:23 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-09-29 00:55:23 -0400 |
| commit | 1c9114f9c0f10f58dd7e568a7152025af47b27e5 (patch) | |
| tree | 1c9fd2798fe34047ffd14030364d71ca64533b55 /fs/ext4 | |
| parent | 17335dcc471199717839b2fa3492ca36f70f1168 (diff) | |
| download | linux-1c9114f9c0f10f58dd7e568a7152025af47b27e5.tar.bz2 | |
ext4: serialize unlocked dio reads with truncate
Current serialization will works only for DIO which holds
i_mutex, but nonlocked DIO following race is possible:
dio_nolock_read_task truncate_task
->ext4_setattr()
->inode_dio_wait()
->ext4_ext_direct_IO
->ext4_ind_direct_IO
->__blockdev_direct_IO
->ext4_get_block
->truncate_setsize()
->ext4_truncate()
#alloc truncated blocks
#to other inode
->submit_io()
#INFORMATION LEAK
In order to serialize with unlocked DIO reads we have to
rearrange wait sequence
1) update i_size first
2) if i_size about to be reduced wait for outstanding DIO requests
3) and only after that truncate inode blocks
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/inode.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index bdd399bc2abf..0bfc63331467 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4283,7 +4283,6 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) } if (attr->ia_valid & ATTR_SIZE) { - inode_dio_wait(inode); if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); @@ -4332,8 +4331,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) } if (attr->ia_valid & ATTR_SIZE) { - if (attr->ia_size != i_size_read(inode)) + if (attr->ia_size != i_size_read(inode)) { truncate_setsize(inode, attr->ia_size); + /* Inode size will be reduced, wait for dio in flight */ + if (orphan) + inode_dio_wait(inode); + } ext4_truncate(inode); } |