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authorDmitry Monakhov <dmonakhov@openvz.org>2012-09-29 00:55:23 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-09-29 00:55:23 -0400
commit1c9114f9c0f10f58dd7e568a7152025af47b27e5 (patch)
tree1c9fd2798fe34047ffd14030364d71ca64533b55 /fs
parent17335dcc471199717839b2fa3492ca36f70f1168 (diff)
downloadop-kernel-dev-1c9114f9c0f10f58dd7e568a7152025af47b27e5.zip
op-kernel-dev-1c9114f9c0f10f58dd7e568a7152025af47b27e5.tar.gz
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')
-rw-r--r--fs/ext4/inode.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bdd399b..0bfc633 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);
}
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