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[PATCH 6/8] xfs: split buffered IO write path from xfs_file_aio_write

To: xfs@xxxxxxxxxxx
Subject: [PATCH 6/8] xfs: split buffered IO write path from xfs_file_aio_write
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 7 Jan 2011 22:30:23 +1100
In-reply-to: <1294399825-1157-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1294399825-1157-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

Complete the split of the different write IO paths by splitting the
buffered IO write path out of xfs_file_aio_write(). This makes the
different mechanisms of the write patchs easier to follow.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Alex Elder <aelder@xxxxxxx>
---
 fs/xfs/linux-2.6/xfs_file.c |  146 ++++++++++++++++++++-----------------------
 1 files changed, 69 insertions(+), 77 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 2d55648..9ce5e12 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -730,58 +730,31 @@ xfs_file_dio_aio_write(
 }
 
 STATIC ssize_t
-xfs_file_aio_write(
+xfs_file_buffered_aio_write(
        struct kiocb            *iocb,
        const struct iovec      *iovp,
        unsigned long           nr_segs,
-       loff_t                  pos)
+       loff_t                  pos,
+       size_t                  ocount,
+       int                     *iolock)
 {
        struct file             *file = iocb->ki_filp;
        struct address_space    *mapping = file->f_mapping;
        struct inode            *inode = mapping->host;
        struct xfs_inode        *ip = XFS_I(inode);
-       struct xfs_mount        *mp = ip->i_mount;
-       ssize_t                 ret = 0;
-       int                     ioflags = 0;
+       ssize_t                 ret;
+       int                     enospc = 0;
        xfs_fsize_t             new_size;
-       int                     iolock;
-       size_t                  ocount = 0, count;
-
-       XFS_STATS_INC(xs_write_calls);
-
-       BUG_ON(iocb->ki_pos != pos);
-
-       if (unlikely(file->f_flags & O_DIRECT))
-               ioflags |= IO_ISDIRECT;
-       if (file->f_mode & FMODE_NOCMTIME)
-               ioflags |= IO_INVIS;
-
-       ret = generic_segment_checks(iovp, &nr_segs, &ocount, VERIFY_READ);
-       if (ret)
-               return ret;
-
-       count = ocount;
-       if (count == 0)
-               return 0;
-
-       xfs_wait_for_freeze(mp, SB_FREEZE_WRITE);
-
-       if (XFS_FORCED_SHUTDOWN(mp))
-               return -EIO;
+       size_t                  count = ocount;
 
-relock:
-       if (ioflags & IO_ISDIRECT) {
-               ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos,
-                                               ocount, &iolock);
-               goto done_io;
-       }
-       iolock = XFS_IOLOCK_EXCL;
+       *iolock = XFS_IOLOCK_EXCL;
+       xfs_rw_ilock(ip, XFS_ILOCK_EXCL|*iolock);
 
-       xfs_rw_ilock(ip, XFS_ILOCK_EXCL|iolock);
        ret = generic_write_checks(file, &pos, &count,
                                        S_ISBLK(inode->i_mode));
        if (ret) {
-               xfs_rw_iunlock(ip, XFS_ILOCK_EXCL|iolock);
+               xfs_rw_iunlock(ip, XFS_ILOCK_EXCL|*iolock);
+               *iolock = 0;
                return ret;
        }
 
@@ -789,67 +762,86 @@ relock:
        if (new_size > ip->i_size)
                ip->i_new_size = new_size;
 
-       if (likely(!(ioflags & IO_INVIS)))
+       if (likely(!(file->f_mode & FMODE_NOCMTIME)))
                file_update_time(file);
 
-       /*
-        * If the offset is beyond the size of the file, we have a couple
-        * of things to do. First, if there is already space allocated
-        * we need to either create holes or zero the disk or ...
-        *
-        * If there is a page where the previous size lands, we need
-        * to zero it out up to the new size.
-        */
-
        if (pos > ip->i_size) {
                ret = -xfs_zero_eof(ip, pos, ip->i_size);
                if (ret) {
                        xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
-                       goto out_unlock_internal;
+                       return ret;
                }
        }
        xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
 
-       /*
-        * If we're writing the file then make sure to clear the
-        * setuid and setgid bits if the process is not being run
-        * by root.  This keeps people from modifying setuid and
-        * setgid binaries.
-        */
        ret = file_remove_suid(file);
        if (unlikely(ret))
-               goto out_unlock_internal;
+               return ret;
 
        /* We can write back this queue in page reclaim */
        current->backing_dev_info = mapping->backing_dev_info;
 
-       if (!(ioflags & IO_ISDIRECT)) {
-               int enospc = 0;
-
 write_retry:
-               trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, ioflags);
-               ret = generic_file_buffered_write(iocb, iovp, nr_segs,
-                               pos, &iocb->ki_pos, count, ret);
-               /*
-                * if we just got an ENOSPC, flush the inode now we
-                * aren't holding any page locks and retry *once*
-                */
-               if (ret == -ENOSPC && !enospc) {
-                       ret = xfs_flush_pages(ip, 0, -1, 0, FI_NONE);
-                       if (ret)
-                               goto out_unlock_internal;
-                       enospc = 1;
-                       goto write_retry;
-               }
+       trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);
+       ret = generic_file_buffered_write(iocb, iovp, nr_segs,
+                       pos, &iocb->ki_pos, count, ret);
+       /*
+        * if we just got an ENOSPC, flush the inode now we aren't holding any
+        * page locks and retry *once*
+        */
+       if (ret == -ENOSPC && !enospc) {
+               ret = -xfs_flush_pages(ip, 0, -1, 0, FI_NONE);
+               if (ret)
+                       return ret;
+               enospc = 1;
+               goto write_retry;
        }
-
        current->backing_dev_info = NULL;
+       return ret;
+}
+
+STATIC ssize_t
+xfs_file_aio_write(
+       struct kiocb            *iocb,
+       const struct iovec      *iovp,
+       unsigned long           nr_segs,
+       loff_t                  pos)
+{
+       struct file             *file = iocb->ki_filp;
+       struct address_space    *mapping = file->f_mapping;
+       struct inode            *inode = mapping->host;
+       struct xfs_inode        *ip = XFS_I(inode);
+       ssize_t                 ret;
+       int                     iolock;
+       size_t                  ocount = 0;
+
+       XFS_STATS_INC(xs_write_calls);
+
+       BUG_ON(iocb->ki_pos != pos);
+
+       ret = generic_segment_checks(iovp, &nr_segs, &ocount, VERIFY_READ);
+       if (ret)
+               return ret;
+
+       if (ocount == 0)
+               return 0;
+
+       xfs_wait_for_freeze(ip->i_mount, SB_FREEZE_WRITE);
+
+       if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+               return -EIO;
+
+       if (unlikely(file->f_flags & O_DIRECT))
+               ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos,
+                                               ocount, &iolock);
+       else
+               ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,
+                                               ocount, &iolock);
 
-done_io:
        xfs_aio_write_isize_update(inode, &iocb->ki_pos, ret);
 
        if (ret <= 0)
-               goto out_unlock_internal;
+               goto out_unlock;
 
        /* Handle various SYNC-type writes */
        if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
@@ -868,7 +860,7 @@ done_io:
                        ret = error2;
        }
 
- out_unlock_internal:
+out_unlock:
        xfs_aio_write_newsize_update(ip);
        xfs_rw_iunlock(ip, iolock);
        return ret;
-- 
1.7.2.3

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