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[CIFS] cifs truncate missing a fix for private map COW race 

vmtruncate had added the same fix to handle the case of private pages
being Copy on writed while truncate_inode_pages is going on

Signed-off-by: Steve French <sfrench@us.ibm.com>
hifive-unleashed-5.1
Steve French 2007-08-22 22:12:07 +00:00
parent cb00e99c0a
commit 8064ab4da1
1 changed files with 9 additions and 0 deletions
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9
fs/cifs/inode.c
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@ -1377,8 +1377,17 @@ static int cifs_vmtruncate(struct inode *inode, loff_t offset)
}
i_size_write(inode, offset);
spin_unlock(&inode->i_lock);
/*
* unmap_mapping_range is called twice, first simply for efficiency
* so that truncate_inode_pages does fewer single-page unmaps. However
* after this first call, and before truncate_inode_pages finishes,
* it is possible for private pages to be COWed, which remain after
* truncate_inode_pages finishes, hence the second unmap_mapping_range
* call must be made for correctness.
*/
unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
truncate_inode_pages(mapping, offset);
unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
goto out_truncate;
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