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udf: Fix race between write(2) and close(2)
Currently write(2) updating i_size and close(2) of the file can race in such a way that udf_truncate_tail_extent() called from udf_file_release() sees old i_size but already new extents added by the running write call. This results in complaints like: UDF-fs: warning (device vdb2): udf_truncate_tail_extent: Too long extent after EOF in inode 877: i_size: 0 lbcount: 1073739776 extent 0+1073739776 UDF-fs: error (device vdb2): udf_truncate_tail_extent: Extent after EOF in inode 877 Fix the problem by grabbing i_mutex in udf_file_release() to be sure i_size is consistent with current state of extent list. Also avoid truncating tail extent unnecessarily when the file is still open for writing. Signed-off-by: Jan Kara <jack@suse.cz>
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1 changed files with 8 additions and 1 deletions
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@ -223,11 +223,18 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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static int udf_release_file(struct inode *inode, struct file *filp)
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{
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if (filp->f_mode & FMODE_WRITE) {
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if (filp->f_mode & FMODE_WRITE &&
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atomic_read(&inode->i_writecount) > 1) {
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/*
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* Grab i_mutex to avoid races with writes changing i_size
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* while we are running.
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*/
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mutex_lock(&inode->i_mutex);
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down_write(&UDF_I(inode)->i_data_sem);
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udf_discard_prealloc(inode);
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udf_truncate_tail_extent(inode);
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up_write(&UDF_I(inode)->i_data_sem);
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mutex_unlock(&inode->i_mutex);
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}
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return 0;
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}
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