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[PATCH 3/8] ext4: Protect ext4_page_mkwrite & ext4_setattr with sb_start

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: [PATCH 3/8] ext4: Protect ext4_page_mkwrite & ext4_setattr with sb_start_write - sb_end_write
From: Jan Kara <jack@xxxxxxx>
Date: Fri, 20 Jan 2012 21:34:41 +0100
Cc: Eric Sandeen <sandeen@xxxxxxxxxxx>, Dave Chinner <dchinner@xxxxxxxxxx>, Surbhi Palande <csurbhi@xxxxxxxxx>, Kamal Mostafa <kamal@xxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, Jan Kara <jack@xxxxxxx>
In-reply-to: <1327091686-23177-1-git-send-email-jack@xxxxxxx>
References: <1327091686-23177-1-git-send-email-jack@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 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

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