1 files changed, 52 insertions, 16 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 8fd4a0708d30..cbbac5cc9c26 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -418,11 +418,13 @@ xfs_aio_write_isize_update(
  */
 STATIC void
 xfs_aio_write_newsize_update(
-        struct xfs_inode        *ip)
+        struct xfs_inode        *ip,
+        xfs_fsize_t             new_size)
 {
-        if (ip->i_new_size) {
+        if (new_size == ip->i_new_size) {
                 xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
-                ip->i_new_size = 0;
+                if (new_size == ip->i_new_size)
+                        ip->i_new_size = 0;
                 if (ip->i_d.di_size > ip->i_size)
                         ip->i_d.di_size = ip->i_size;
                 xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
@@ -473,7 +475,7 @@ xfs_file_splice_write(
         ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
 
         xfs_aio_write_isize_update(inode, ppos, ret);
-        xfs_aio_write_newsize_update(ip);
+        xfs_aio_write_newsize_update(ip, new_size);
         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
         return ret;
 }
@@ -670,6 +672,7 @@ 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;
@@ -677,6 +680,8 @@ xfs_file_aio_write_checks(
         xfs_fsize_t             new_size;
         int                     error = 0;
 
+        *new_sizep = 0;
+restart:
         error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
         if (error) {
                 xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);
@@ -684,20 +689,41 @@ xfs_file_aio_write_checks(
                 return error;
         }
 
-        new_size = *pos + *count;
-        if (new_size > ip->i_size)
-                ip->i_new_size = new_size;
-
         if (likely(!(file->f_mode & FMODE_NOCMTIME)))
                 file_update_time(file);
 
         /*
          * 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.
+         * 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.
          */
-        if (*pos > ip->i_size)
+        if ((ip->i_new_size && *pos > ip->i_new_size) ||
+            (!ip->i_new_size && *pos > ip->i_size)) {
+                if (*iolock == XFS_IOLOCK_SHARED) {
+                        xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);
+                        *iolock = XFS_IOLOCK_EXCL;
+                        xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
+                        goto restart;
+                }
                 error = -xfs_zero_eof(ip, *pos, ip->i_size);
+        }
+
+        /*
+         * 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 > ip->i_size) {
+                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)
@@ -744,6 +770,7 @@ 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;
@@ -764,13 +791,20 @@ xfs_file_dio_aio_write(
         if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))
                 unaligned_io = 1;
 
-        if (unaligned_io || mapping->nrpages || pos > ip->i_size)
+        /*
+         * We don't need to take an exclusive lock unless there page cache needs
+         * to be invalidated or unaligned IO is being executed. We don't need to
+         * consider the EOF extension case here because
+         * xfs_file_aio_write_checks() will relock the inode as necessary for
+         * EOF zeroing cases and fill out the new inode size as appropriate.
+         */
+        if (unaligned_io || mapping->nrpages)
                 *iolock = XFS_IOLOCK_EXCL;
         else
                 *iolock = XFS_IOLOCK_SHARED;
         xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
 
-        ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
+        ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);
         if (ret)
                 return ret;
 
@@ -809,6 +843,7 @@ 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;
@@ -822,7 +857,7 @@ xfs_file_buffered_aio_write(
         *iolock = XFS_IOLOCK_EXCL;
         xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
 
-        ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
+        ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);
         if (ret)
                 return ret;
 
@@ -862,6 +897,7 @@ 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);
 
@@ -881,10 +917,10 @@ xfs_file_aio_write(
 
         if (unlikely(file->f_flags & O_DIRECT))
                 ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos,
-                                                ocount, &iolock);
+                                                ocount, &new_size, &iolock);
         else
                 ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,
-                                                ocount, &iolock);
+                                                ocount, &new_size, &iolock);
 
         xfs_aio_write_isize_update(inode, &iocb->ki_pos, ret);
 
@@ -905,7 +941,7 @@ xfs_file_aio_write(
         }
 
 out_unlock:
-        xfs_aio_write_newsize_update(ip);
+        xfs_aio_write_newsize_update(ip, new_size);
         xfs_rw_iunlock(ip, iolock);
         return ret;
 }