diff options
| -rw-r--r-- | fs/xfs/xfs_aops.c | 7 | ||||
| -rw-r--r-- | fs/xfs/xfs_file.c | 13 |
2 files changed, 19 insertions, 1 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index c02a47453137..598b259fda04 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -1582,9 +1582,16 @@ xfs_end_io_direct_write( * with the on-disk inode size being outside the in-core inode size. We * have no other method of updating EOF for AIO, so always do it here * if necessary. + * + * We need to lock the test/set EOF update as we can be racing with + * other IO completions here to update the EOF. Failing to serialise + * here can result in EOF moving backwards and Bad Things Happen when + * that occurs. */ + spin_lock(&ip->i_flags_lock); if (offset + size > i_size_read(inode)) i_size_write(inode, offset + size); + spin_unlock(&ip->i_flags_lock); /* * If we are doing an append IO that needs to update the EOF on disk, diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index ce615d12fb44..2323b8b63183 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -565,8 +565,18 @@ restart: * write. If zeroing is needed and we are currently holding the * iolock shared, we need to update it to exclusive which implies * having to redo all checks before. + * + * We need to serialise against EOF updates that occur in IO + * completions here. We want to make sure that nobody is changing the + * size while we do this check until we have placed an IO barrier (i.e. + * hold the XFS_IOLOCK_EXCL) that prevents new IO from being dispatched. + * The spinlock effectively forms a memory barrier once we have the + * XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value + * and hence be able to correctly determine if we need to run zeroing. */ + spin_lock(&ip->i_flags_lock); if (*pos > i_size_read(inode)) { + spin_unlock(&ip->i_flags_lock); if (*iolock == XFS_IOLOCK_SHARED) { xfs_rw_iunlock(ip, *iolock); *iolock = XFS_IOLOCK_EXCL; @@ -576,7 +586,8 @@ restart: error = xfs_zero_eof(ip, *pos, i_size_read(inode)); if (error) return error; - } + } else + spin_unlock(&ip->i_flags_lock); /* * Updating the timestamps will grab the ilock again from |