xfs: remove the i_new_size field in struct xfs_inode

Now that we use the VFS i_size field throughout XFS there is no need for the
i_new_size field any more given that the VFS i_size field gets updated
in ->write_end before unlocking the page, and thus is always uptodate when
writeback could see a page.  Removing i_new_size also has the advantage that
we will never have to trim back di_size during a failed buffered write,
given that it never gets updated past i_size.

Note that currently the generic direct I/O code only updates i_size after
calling our end_io handler, which requires a small workaround to make
sure di_size actually makes it to disk.  I hope to fix this properly in
the generic code.

A downside is that we lose the support for parallel non-overlapping O_DIRECT
appending writes that recently was added.  I don't think keeping the complex
and fragile i_new_size infrastructure for this is a good tradeoff - if we
really care about parallel appending writers we should investigate turning
the iolock into a range lock, which would also allow for parallel
non-overlapping buffered writers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

5 files changed, 30 insertions, 92 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 4d27ea117e0e..74b9baf36ac3 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -111,8 +111,7 @@ xfs_ioend_new_eof(
         xfs_fsize_t             bsize;
 
         bsize = ioend->io_offset + ioend->io_size;
-        isize = MAX(i_size_read(VFS_I(ip)), ip->i_new_size);
-        isize = MIN(isize, bsize);
+        isize = MIN(i_size_read(VFS_I(ip)), bsize);
         return isize > ip->i_d.di_size ? isize : 0;
 }
 
@@ -126,11 +125,7 @@ static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
 }
 
 /*
- * Update on-disk file size now that data has been written to disk.  The
- * current in-memory file size is i_size.  If a write is beyond eof i_new_size
- * will be the intended file size until i_size is updated.  If this write does
- * not extend all the way to the valid file size then restrict this update to
- * the end of the write.
+ * Update on-disk file size now that data has been written to disk.
  *
  * This function does not block as blocking on the inode lock in IO completion
  * can lead to IO completion order dependency deadlocks.. If it can't get the
@@ -1279,6 +1274,15 @@ xfs_end_io_direct_write(
         struct xfs_ioend        *ioend = iocb->private;
 
         /*
+         * While the generic direct I/O code updates the inode size, it does
+         * so only after the end_io handler is called, which means our
+         * end_io handler thinks the on-disk size is outside the in-core
+         * size.  To prevent this just update it a little bit earlier here.
+         */
+        if (offset + size > i_size_read(ioend->io_inode))
+                i_size_write(ioend->io_inode, offset + size);
+
+        /*
          * blockdev_direct_IO can return an error even after the I/O
          * completion handler was called.  Thus we need to protect
          * against double-freeing.
@@ -1340,12 +1344,11 @@ xfs_vm_write_failed(
 
         if (to > inode->i_size) {
                 /*
-                 * punch out the delalloc blocks we have already allocated. We
-                 * don't call xfs_setattr() to do this as we may be in the
-                 * middle of a multi-iovec write and so the vfs inode->i_size
-                 * will not match the xfs ip->i_size and so it will zero too
-                 * much. Hence we jus truncate the page cache to zero what is
-                 * necessary and punch the delalloc blocks directly.
+                 * Punch out the delalloc blocks we have already allocated.
+                 *
+                 * Don't bother with xfs_setattr given that nothing can have
+                 * made it to disk yet as the page is still locked at this
+                 * point.
                  */
                 struct xfs_inode        *ip = XFS_I(inode);
                 xfs_fileoff_t           start_fsb;
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 86d5dc260464..632313926788 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -413,27 +413,6 @@ xfs_file_splice_read(
 }
 
 /*
- * If this was a direct or synchronous I/O that failed (such as ENOSPC) then
- * part of the I/O may have been written to disk before the error occurred.  In
- * this case the on-disk file size may have been adjusted beyond the in-memory
- * file size and now needs to be truncated back.
- */
-STATIC void
-xfs_aio_write_newsize_update(
-        struct xfs_inode        *ip,
-        xfs_fsize_t             new_size)
-{
-        if (new_size == ip->i_new_size) {
-                xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
-                if (new_size == ip->i_new_size)
-                        ip->i_new_size = 0;
-                if (ip->i_d.di_size > i_size_read(VFS_I(ip)))
-                        ip->i_d.di_size = i_size_read(VFS_I(ip));
-                xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
-        }
-}
-
-/*
  * xfs_file_splice_write() does not use xfs_rw_ilock() because
  * generic_file_splice_write() takes the i_mutex itself. This, in theory,
  * couuld cause lock inversions between the aio_write path and the splice path
@@ -451,7 +430,6 @@ xfs_file_splice_write(
 {
         struct inode            *inode = outfilp->f_mapping->host;
         struct xfs_inode        *ip = XFS_I(inode);
-        xfs_fsize_t             new_size;
         int                     ioflags = 0;
         ssize_t                 ret;
 
@@ -465,20 +443,12 @@ xfs_file_splice_write(
 
         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 
-        new_size = *ppos + count;
-
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
-        if (new_size > i_size_read(inode))
-                ip->i_new_size = new_size;
-        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
         trace_xfs_file_splice_write(ip, count, *ppos, ioflags);
 
         ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
         if (ret > 0)
                 XFS_STATS_ADD(xs_write_bytes, ret);
 
-        xfs_aio_write_newsize_update(ip, new_size);
         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
         return ret;
 }
@@ -673,16 +643,13 @@ xfs_file_aio_write_checks(
         struct file             *file,
         loff_t                  *pos,
         size_t                  *count,
-        xfs_fsize_t             *new_sizep,
         int                     *iolock)
 {
         struct inode            *inode = file->f_mapping->host;
         struct xfs_inode        *ip = XFS_I(inode);
-        xfs_fsize_t             new_size;
         int                     error = 0;
 
         xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
-        *new_sizep = 0;
 restart:
         error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
         if (error) {
@@ -697,15 +664,13 @@ restart:
         /*
          * If the offset is beyond the size of the file, we need to zero any
          * blocks that fall between the existing EOF and the start of this
-         * write. There is no need to issue zeroing if another in-flght IO ends
-         * at or before this one If zeronig is needed and we are currently
-         * holding the iolock shared, we need to update it to exclusive which
-         * involves dropping all locks and relocking to maintain correct locking
-         * order. If we do this, restart the function to ensure all checks and
-         * values are still valid.
+         * write.  If zeroing is needed and we are currently holding the
+         * iolock shared, we need to update it to exclusive which involves
+         * dropping all locks and relocking to maintain correct locking order.
+         * If we do this, restart the function to ensure all checks and values
+         * are still valid.
          */
-        if ((ip->i_new_size && *pos > ip->i_new_size) ||
-            (!ip->i_new_size && *pos > i_size_read(inode))) {
+        if (*pos > i_size_read(inode)) {
                 if (*iolock == XFS_IOLOCK_SHARED) {
                         xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);
                         *iolock = XFS_IOLOCK_EXCL;
@@ -714,19 +679,6 @@ restart:
                 }
                 error = -xfs_zero_eof(ip, *pos, i_size_read(inode));
         }
-
-        /*
-         * If this IO extends beyond EOF, we may need to update ip->i_new_size.
-         * We have already zeroed space beyond EOF (if necessary).  Only update
-         * ip->i_new_size if this IO ends beyond any other in-flight writes.
-         */
-        new_size = *pos + *count;
-        if (new_size > i_size_read(inode)) {
-                if (new_size > ip->i_new_size)
-                        ip->i_new_size = new_size;
-                *new_sizep = new_size;
-        }
-
         xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
         if (error)
                 return error;
@@ -772,7 +724,6 @@ xfs_file_dio_aio_write(
         unsigned long           nr_segs,
         loff_t                  pos,
         size_t                  ocount,
-        xfs_fsize_t             *new_size,
         int                     *iolock)
 {
         struct file             *file = iocb->ki_filp;
@@ -817,7 +768,7 @@ xfs_file_dio_aio_write(
                 xfs_rw_ilock(ip, *iolock);
         }
 
-        ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);
+        ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
         if (ret)
                 return ret;
 
@@ -855,7 +806,6 @@ xfs_file_buffered_aio_write(
         unsigned long           nr_segs,
         loff_t                  pos,
         size_t                  ocount,
-        xfs_fsize_t             *new_size,
         int                     *iolock)
 {
         struct file             *file = iocb->ki_filp;
@@ -869,7 +819,7 @@ xfs_file_buffered_aio_write(
         *iolock = XFS_IOLOCK_EXCL;
         xfs_rw_ilock(ip, *iolock);
 
-        ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);
+        ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
         if (ret)
                 return ret;
 
@@ -909,7 +859,6 @@ xfs_file_aio_write(
         ssize_t                 ret;
         int                     iolock;
         size_t                  ocount = 0;
-        xfs_fsize_t             new_size = 0;
 
         XFS_STATS_INC(xs_write_calls);
 
@@ -929,10 +878,10 @@ xfs_file_aio_write(
 
         if (unlikely(file->f_flags & O_DIRECT))
                 ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos,
-                                                ocount, &new_size, &iolock);
+                                                ocount, &iolock);
         else
                 ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,
-                                                ocount, &new_size, &iolock);
+                                                ocount, &iolock);
 
         if (ret <= 0)
                 goto out_unlock;
@@ -953,7 +902,6 @@ xfs_file_aio_write(
         }
 
 out_unlock:
-        xfs_aio_write_newsize_update(ip, new_size);
         xfs_rw_iunlock(ip, iolock);
         return ret;
 }
diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index 3b5b78aa3b87..8c3e46394d48 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -94,7 +94,6 @@ xfs_inode_alloc(
         ip->i_update_core = 0;
         ip->i_delayed_blks = 0;
         memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));
-        ip->i_new_size = 0;
 
         return ip;
 }
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index cd99e43fa8f0..2f27b7454085 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -246,8 +246,6 @@ typedef struct xfs_inode {
 
         xfs_icdinode_t          i_d;            /* most of ondisk inode */
 
-        xfs_fsize_t             i_new_size;     /* size when write completes */
-
         /* VFS inode */
         struct inode            i_vnode;        /* embedded VFS inode */
 } xfs_inode_t;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 2aabcc9c507e..6b6df5802e95 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -891,7 +891,6 @@ DECLARE_EVENT_CLASS(xfs_file_class,
                 __field(dev_t, dev)
                 __field(xfs_ino_t, ino)
                 __field(xfs_fsize_t, size)
-                __field(xfs_fsize_t, new_size)
                 __field(loff_t, offset)
                 __field(size_t, count)
                 __field(int, flags)
@@ -900,17 +899,15 @@ DECLARE_EVENT_CLASS(xfs_file_class,
                 __entry->dev = VFS_I(ip)->i_sb->s_dev;
                 __entry->ino = ip->i_ino;
                 __entry->size = ip->i_d.di_size;
-                __entry->new_size = ip->i_new_size;
                 __entry->offset = offset;
                 __entry->count = count;
                 __entry->flags = flags;
         ),
-        TP_printk("dev %d:%d ino 0x%llx size 0x%llx new_size 0x%llx "
+        TP_printk("dev %d:%d ino 0x%llx size 0x%llx "
                   "offset 0x%llx count 0x%zx ioflags %s",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   __entry->ino,
                   __entry->size,
-                  __entry->new_size,
                   __entry->offset,
                   __entry->count,
                   __print_flags(__entry->flags, "|", XFS_IO_FLAGS))
@@ -978,7 +975,6 @@ DECLARE_EVENT_CLASS(xfs_imap_class,
                 __field(dev_t, dev)
                 __field(xfs_ino_t, ino)
                 __field(loff_t, size)
-                __field(loff_t, new_size)
                 __field(loff_t, offset)
                 __field(size_t, count)
                 __field(int, type)
@@ -990,7 +986,6 @@ DECLARE_EVENT_CLASS(xfs_imap_class,
                 __entry->dev = VFS_I(ip)->i_sb->s_dev;
                 __entry->ino = ip->i_ino;
                 __entry->size = ip->i_d.di_size;
-                __entry->new_size = ip->i_new_size;
                 __entry->offset = offset;
                 __entry->count = count;
                 __entry->type = type;
@@ -998,13 +993,11 @@ DECLARE_EVENT_CLASS(xfs_imap_class,
                 __entry->startblock = irec ? irec->br_startblock : 0;
                 __entry->blockcount = irec ? irec->br_blockcount : 0;
         ),
-        TP_printk("dev %d:%d ino 0x%llx size 0x%llx new_size 0x%llx "
-                  "offset 0x%llx count %zd type %s "
-                  "startoff 0x%llx startblock %lld blockcount 0x%llx",
+        TP_printk("dev %d:%d ino 0x%llx size 0x%llx offset 0x%llx count %zd "
+                  "type %s startoff 0x%llx startblock %lld blockcount 0x%llx",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   __entry->ino,
                   __entry->size,
-                  __entry->new_size,
                   __entry->offset,
                   __entry->count,
                   __print_symbolic(__entry->type, XFS_IO_TYPES),
@@ -1031,7 +1024,6 @@ DECLARE_EVENT_CLASS(xfs_simple_io_class,
                 __field(xfs_ino_t, ino)
                 __field(loff_t, isize)
                 __field(loff_t, disize)
-                __field(loff_t, new_size)
                 __field(loff_t, offset)
                 __field(size_t, count)
         ),
@@ -1040,17 +1032,15 @@ DECLARE_EVENT_CLASS(xfs_simple_io_class,
                 __entry->ino = ip->i_ino;
                 __entry->isize = VFS_I(ip)->i_size;
                 __entry->disize = ip->i_d.di_size;
-                __entry->new_size = ip->i_new_size;
                 __entry->offset = offset;
                 __entry->count = count;
         ),
-        TP_printk("dev %d:%d ino 0x%llx isize 0x%llx disize 0x%llx new_size 0x%llx "
+        TP_printk("dev %d:%d ino 0x%llx isize 0x%llx disize 0x%llx "
                   "offset 0x%llx count %zd",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
                   __entry->ino,
                   __entry->isize,
                   __entry->disize,
-                  __entry->new_size,
                   __entry->offset,
                   __entry->count)
 );