xfs: don't do IO when creating an new inode
When we are allocating a new inode, we read the inode cluster off disk to increment the generation number. We are already using a random generation number for newly allocated inodes, so if we are not using the ikeep mode, we can just generate a new generation number when we initialise the newly allocated inode. This avoids the need for reading the inode buffer during inode creation. This will speed up allocation of inodes in cold, partially allocated clusters as they will no longer need to be read from disk during allocation. It will also reduce the CPU overhead of inode allocation by not having the process the buffer read, even on cache hits. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
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@ -1028,6 +1028,11 @@ xfs_dinode_calc_crc(
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/*
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/*
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* Read the disk inode attributes into the in-core inode structure.
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* Read the disk inode attributes into the in-core inode structure.
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*
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* If we are initialising a new inode and we are not utilising the
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* XFS_MOUNT_IKEEP inode cluster mode, we can simple build the new inode core
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* with a random generation number. If we are keeping inodes around, we need to
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* read the inode cluster to get the existing generation number off disk.
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*/
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*/
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int
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int
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xfs_iread(
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xfs_iread(
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@ -1047,6 +1052,22 @@ xfs_iread(
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if (error)
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if (error)
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return error;
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return error;
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/* shortcut IO on inode allocation if possible */
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if ((iget_flags & XFS_IGET_CREATE) &&
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!(mp->m_flags & XFS_MOUNT_IKEEP)) {
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/* initialise the on-disk inode core */
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memset(&ip->i_d, 0, sizeof(ip->i_d));
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ip->i_d.di_magic = XFS_DINODE_MAGIC;
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ip->i_d.di_gen = prandom_u32();
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if (xfs_sb_version_hascrc(&mp->m_sb)) {
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ip->i_d.di_version = 3;
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ip->i_d.di_ino = ip->i_ino;
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uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
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} else
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ip->i_d.di_version = 2;
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return 0;
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}
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/*
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/*
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* Get pointers to the on-disk inode and the buffer containing it.
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* Get pointers to the on-disk inode and the buffer containing it.
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*/
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*/
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@ -1133,17 +1154,16 @@ xfs_iread(
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xfs_buf_set_ref(bp, XFS_INO_REF);
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xfs_buf_set_ref(bp, XFS_INO_REF);
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/*
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/*
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* Use xfs_trans_brelse() to release the buffer containing the
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* Use xfs_trans_brelse() to release the buffer containing the on-disk
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* on-disk inode, because it was acquired with xfs_trans_read_buf()
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* inode, because it was acquired with xfs_trans_read_buf() in
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* in xfs_imap_to_bp() above. If tp is NULL, this is just a normal
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* xfs_imap_to_bp() above. If tp is NULL, this is just a normal
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* brelse(). If we're within a transaction, then xfs_trans_brelse()
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* brelse(). If we're within a transaction, then xfs_trans_brelse()
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* will only release the buffer if it is not dirty within the
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* will only release the buffer if it is not dirty within the
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* transaction. It will be OK to release the buffer in this case,
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* transaction. It will be OK to release the buffer in this case,
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* because inodes on disk are never destroyed and we will be
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* because inodes on disk are never destroyed and we will be locking the
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* locking the new in-core inode before putting it in the hash
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* new in-core inode before putting it in the cache where other
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* table where other processes can find it. Thus we don't have
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* processes can find it. Thus we don't have to worry about the inode
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* to worry about the inode being changed just because we released
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* being changed just because we released the buffer.
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* the buffer.
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*/
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*/
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out_brelse:
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out_brelse:
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xfs_trans_brelse(tp, bp);
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xfs_trans_brelse(tp, bp);
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