ext4: Fix ext4_quota_write cross block boundary behaviour
We always assume what dquot update result in changes in one data block But ext4_quota_write() function may handle cross block boundary writes In fact if this ever happen it will result in incorrect journal credits reservation, and later a BUG_ON. As soon this never happen the boundary cross loop is NOOP. In order to make things straight let's remove this loop and assert cross boundary condition. Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -4010,9 +4010,7 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
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ext4_lblk_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
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int err = 0;
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int offset = off & (sb->s_blocksize - 1);
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int tocopy;
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int journal_quota = EXT4_SB(sb)->s_qf_names[type] != NULL;
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size_t towrite = len;
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struct buffer_head *bh;
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handle_t *handle = journal_current_handle();
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@ -4022,52 +4020,53 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
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(unsigned long long)off, (unsigned long long)len);
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return -EIO;
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}
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mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
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while (towrite > 0) {
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tocopy = sb->s_blocksize - offset < towrite ?
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sb->s_blocksize - offset : towrite;
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bh = ext4_bread(handle, inode, blk, 1, &err);
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if (!bh)
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goto out;
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if (journal_quota) {
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err = ext4_journal_get_write_access(handle, bh);
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if (err) {
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brelse(bh);
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goto out;
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}
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}
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lock_buffer(bh);
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memcpy(bh->b_data+offset, data, tocopy);
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flush_dcache_page(bh->b_page);
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unlock_buffer(bh);
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if (journal_quota)
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err = ext4_handle_dirty_metadata(handle, NULL, bh);
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else {
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/* Always do at least ordered writes for quotas */
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err = ext4_jbd2_file_inode(handle, inode);
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mark_buffer_dirty(bh);
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}
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brelse(bh);
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if (err)
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goto out;
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offset = 0;
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towrite -= tocopy;
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data += tocopy;
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blk++;
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/*
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* Since we account only one data block in transaction credits,
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* then it is impossible to cross a block boundary.
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*/
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if (sb->s_blocksize - offset < len) {
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ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
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" cancelled because not block aligned",
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(unsigned long long)off, (unsigned long long)len);
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return -EIO;
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}
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mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
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bh = ext4_bread(handle, inode, blk, 1, &err);
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if (!bh)
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goto out;
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if (journal_quota) {
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err = ext4_journal_get_write_access(handle, bh);
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if (err) {
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brelse(bh);
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goto out;
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}
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}
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lock_buffer(bh);
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memcpy(bh->b_data+offset, data, len);
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flush_dcache_page(bh->b_page);
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unlock_buffer(bh);
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if (journal_quota)
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err = ext4_handle_dirty_metadata(handle, NULL, bh);
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else {
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/* Always do at least ordered writes for quotas */
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err = ext4_jbd2_file_inode(handle, inode);
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mark_buffer_dirty(bh);
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}
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brelse(bh);
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out:
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if (len == towrite) {
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if (err) {
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mutex_unlock(&inode->i_mutex);
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return err;
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}
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if (inode->i_size < off+len-towrite) {
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i_size_write(inode, off+len-towrite);
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if (inode->i_size < off + len) {
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i_size_write(inode, off + len);
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EXT4_I(inode)->i_disksize = inode->i_size;
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}
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inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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ext4_mark_inode_dirty(handle, inode);
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mutex_unlock(&inode->i_mutex);
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return len - towrite;
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return len;
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}
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#endif
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