[PATCH 3/8] ext4: Protect ext4_page_mkwrite & ext4_setattr with sb_start_write - sb_end_write

Jan Kara
2012-01-20T20:34:59Z

Since ext4_page_mkwrite() calls into __block_page_mkwrite() it has to
provide freezing protection on it's own. Also ext4_setattr() needs protection
because ext4_truncate() can modify last page of the file.

Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/ext4/inode.c | 9 ++++-----
1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 848f436..05d6328 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4225,6 +4225,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
if (error)
return error;

+ sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
if (is_quota_modification(inode, attr))
dquot_initialize(inode);
if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
@@ -4327,6 +4328,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
rc = ext4_acl_chmod(inode);

err_out:
+ sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
ext4_std_error(inode->i_sb, error);
if (!error)
error = rc;
@@ -4733,11 +4735,7 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
get_block_t *get_block;
int retries = 0;

- /*
- * This check is racy but catches the common case. We rely on
- * __block_page_mkwrite() to do a reliable check.
- */
- vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+ sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
/* Delalloc case is easy... */
if (test_opt(inode->i_sb, DELALLOC) &&
!ext4_should_journal_data(inode) &&
@@ -4805,5 +4803,6 @@ retry_alloc:
out_ret:
ret = block_page_mkwrite_return(ret);
out:
+ sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
return ret;
}
--
1.7.1