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xfs: don't block on the ilock for RWF_NOWAIT 

Fix xfs_file_iomap_begin to trylock the ilock if IOMAP_NOWAIT is passed,
so that we don't block io_submit callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2018-03-01 14:12:45 -08:00 committed by Darrick J. Wong
parent af5b5afe9a
commit ff3d8b9c4c
1 changed files with 19 additions and 8 deletions
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27
fs/xfs/xfs_iomap.c
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@ -970,6 +970,15 @@ static inline bool need_excl_ilock(struct xfs_inode *ip, unsigned flags)
*/
if (xfs_is_reflink_inode(ip) && (flags & (IOMAP_WRITE | IOMAP_ZERO)))
return true;
/*
* Extents not yet cached requires exclusive access, don't block.
* This is an opencoded xfs_ilock_data_map_shared() to cater for the
* non-blocking behaviour.
*/
if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
!(ip->i_df.if_flags & XFS_IFEXTENTS))
return true;
return false;
}
@ -998,16 +1007,18 @@ xfs_file_iomap_begin(
return xfs_file_iomap_begin_delay(inode, offset, length, iomap);
}
if (need_excl_ilock(ip, flags)) {
if (need_excl_ilock(ip, flags))
lockmode = XFS_ILOCK_EXCL;
xfs_ilock(ip, XFS_ILOCK_EXCL);
} else {
lockmode = xfs_ilock_data_map_shared(ip);
}
else
lockmode = XFS_ILOCK_SHARED;
if ((flags & IOMAP_NOWAIT) && !(ip->i_df.if_flags & XFS_IFEXTENTS)) {
error = -EAGAIN;
goto out_unlock;
if (flags & IOMAP_NOWAIT) {
if (!(ip->i_df.if_flags & XFS_IFEXTENTS))
return -EAGAIN;
if (!xfs_ilock_nowait(ip, lockmode))
return -EAGAIN;
} else {
xfs_ilock(ip, lockmode);
}
ASSERT(offset <= mp->m_super->s_maxbytes);