From c891c30a4dd1a236bb98630b35fc2769c5ce0d40 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Wed, 20 Jul 2016 11:13:43 +1000 Subject: [PATCH] xfs: exclude never-released buffers from buftarg I/O accounting The upcoming buftarg I/O accounting mechanism maintains a count of all buffers that have undergone I/O in the current hold-release cycle. Certain buffers associated with core infrastructure (e.g., the xfs_mount superblock buffer, log buffers) are never released, however. This means that accounting I/O submission on such buffers elevates the buftarg count indefinitely and could lead to lockup on unmount. Define a new buffer flag to explicitly exclude buffers from buftarg I/O accounting. Set the flag on the superblock and associated log buffers. Signed-off-by: Brian Foster Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/xfs/xfs_buf.c | 3 ++- fs/xfs/xfs_buf.h | 1 + fs/xfs/xfs_log.c | 5 +++-- fs/xfs/xfs_mount.c | 10 ++++++---- 4 files changed, 12 insertions(+), 7 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 5d52e44b89f7..c0bd5e0b244a 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -815,7 +815,8 @@ xfs_buf_get_uncached( struct xfs_buf *bp; DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks); - bp = _xfs_buf_alloc(target, &map, 1, 0); + /* flags might contain irrelevant bits, pass only what we care about */ + bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT); if (unlikely(bp == NULL)) goto fail; diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h index 8bfb974f0772..e2108dab82a2 100644 --- a/fs/xfs/xfs_buf.h +++ b/fs/xfs/xfs_buf.h @@ -43,6 +43,7 @@ typedef enum { #define XBF_READ (1 << 0) /* buffer intended for reading from device */ #define XBF_WRITE (1 << 1) /* buffer intended for writing to device */ #define XBF_READ_AHEAD (1 << 2) /* asynchronous read-ahead */ +#define XBF_NO_IOACCT (1 << 3) /* bypass I/O accounting (non-LRU bufs) */ #define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */ #define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */ #define XBF_STALE (1 << 6) /* buffer has been staled, do not find it */ diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index bde02f1fba73..216aaa2d9468 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1415,7 +1415,7 @@ xlog_alloc_log( */ error = -ENOMEM; bp = xfs_buf_alloc(mp->m_logdev_targp, XFS_BUF_DADDR_NULL, - BTOBB(log->l_iclog_size), 0); + BTOBB(log->l_iclog_size), XBF_NO_IOACCT); if (!bp) goto out_free_log; @@ -1454,7 +1454,8 @@ xlog_alloc_log( prev_iclog = iclog; bp = xfs_buf_get_uncached(mp->m_logdev_targp, - BTOBB(log->l_iclog_size), 0); + BTOBB(log->l_iclog_size), + XBF_NO_IOACCT); if (!bp) goto out_free_iclog; diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index e39b02351b4a..970c19ba2f56 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -272,13 +272,15 @@ xfs_readsb( buf_ops = NULL; /* - * Allocate a (locked) buffer to hold the superblock. - * This will be kept around at all times to optimize - * access to the superblock. + * Allocate a (locked) buffer to hold the superblock. This will be kept + * around at all times to optimize access to the superblock. Therefore, + * set XBF_NO_IOACCT to make sure it doesn't hold the buftarg count + * elevated. */ reread: error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR, - BTOBB(sector_size), 0, &bp, buf_ops); + BTOBB(sector_size), XBF_NO_IOACCT, &bp, + buf_ops); if (error) { if (loud) xfs_warn(mp, "SB validate failed with error %d.", error);