xfs: optimize inline symlinks
By overallocating the in-core inode fork data buffer and zero
terminating the link target in xfs_init_local_fork we can avoid
the memory allocation in ->follow_link.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 86a97f8..4fbe226 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -239,19 +239,33 @@
int size)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
- int real_size = 0;
+ int mem_size = size, real_size = 0;
+ bool zero_terminate;
+
+ /*
+ * If we are using the local fork to store a symlink body we need to
+ * zero-terminate it so that we can pass it back to the VFS directly.
+ * Overallocate the in-memory fork by one for that and add a zero
+ * to terminate it below.
+ */
+ zero_terminate = S_ISLNK(VFS_I(ip)->i_mode);
+ if (zero_terminate)
+ mem_size++;
if (size == 0)
ifp->if_u1.if_data = NULL;
- else if (size <= sizeof(ifp->if_u2.if_inline_data))
+ else if (mem_size <= sizeof(ifp->if_u2.if_inline_data))
ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
else {
- real_size = roundup(size, 4);
+ real_size = roundup(mem_size, 4);
ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP | KM_NOFS);
}
- if (size)
+ if (size) {
memcpy(ifp->if_u1.if_data, data, size);
+ if (zero_terminate)
+ ifp->if_u1.if_data[size] = '\0';
+ }
ifp->if_bytes = size;
ifp->if_real_bytes = real_size;
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index c48b5b1..37e23c7 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -210,7 +210,7 @@
*/
data_bytes = roundup(ip->i_df.if_bytes, 4);
ASSERT(ip->i_df.if_real_bytes == 0 ||
- ip->i_df.if_real_bytes == data_bytes);
+ ip->i_df.if_real_bytes >= data_bytes);
ASSERT(ip->i_df.if_u1.if_data != NULL);
ASSERT(ip->i_d.di_size > 0);
xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_ILOCAL,
@@ -305,7 +305,7 @@
*/
data_bytes = roundup(ip->i_afp->if_bytes, 4);
ASSERT(ip->i_afp->if_real_bytes == 0 ||
- ip->i_afp->if_real_bytes == data_bytes);
+ ip->i_afp->if_real_bytes >= data_bytes);
ASSERT(ip->i_afp->if_u1.if_data != NULL);
xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_IATTR_LOCAL,
ip->i_afp->if_u1.if_data,
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index f08d91c..aee06d9 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -446,6 +446,16 @@
return ERR_PTR(error);
}
+STATIC const char *
+xfs_vn_get_link_inline(
+ struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ ASSERT(XFS_I(inode)->i_df.if_flags & XFS_IFINLINE);
+ return XFS_I(inode)->i_df.if_u1.if_data;
+}
+
STATIC int
xfs_vn_getattr(
struct vfsmount *mnt,
@@ -1171,6 +1181,18 @@
.update_time = xfs_vn_update_time,
};
+static const struct inode_operations xfs_inline_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .get_link = xfs_vn_get_link_inline,
+ .getattr = xfs_vn_getattr,
+ .setattr = xfs_vn_setattr,
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .removexattr = generic_removexattr,
+ .listxattr = xfs_vn_listxattr,
+ .update_time = xfs_vn_update_time,
+};
+
STATIC void
xfs_diflags_to_iflags(
struct inode *inode,
@@ -1282,9 +1304,10 @@
inode->i_fop = &xfs_dir_file_operations;
break;
case S_IFLNK:
- inode->i_op = &xfs_symlink_inode_operations;
- if (!(ip->i_df.if_flags & XFS_IFINLINE))
- inode->i_mapping->a_ops = &xfs_address_space_operations;
+ if (ip->i_df.if_flags & XFS_IFINLINE)
+ inode->i_op = &xfs_inline_symlink_inode_operations;
+ else
+ inode->i_op = &xfs_symlink_inode_operations;
break;
default:
inode->i_op = &xfs_inode_operations;
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index b69f4a7..5961c1e8 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -131,6 +131,8 @@
trace_xfs_readlink(ip);
+ ASSERT(!(ip->i_df.if_flags & XFS_IFINLINE));
+
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
@@ -150,12 +152,7 @@
}
- if (ip->i_df.if_flags & XFS_IFINLINE) {
- memcpy(link, ip->i_df.if_u1.if_data, pathlen);
- link[pathlen] = '\0';
- } else {
- error = xfs_readlink_bmap(ip, link);
- }
+ error = xfs_readlink_bmap(ip, link);
out:
xfs_iunlock(ip, XFS_ILOCK_SHARED);
