[PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in response to fallocate

Dan Williams
2017-08-04T02:32:47Z

After validating the state of the file as not having holes, shared
extents, or active mappings try to commit the
XFS_DIFLAG2_IOMAP_IMMUTABLE flag to the on-disk inode metadata. If that
succeeds then allow the S_IOMAP_IMMUTABLE to be set on the vfs inode.

Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Suggested-by: "Darrick J. Wong" <darrick.wong@oracle.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/xfs/xfs_bmap_util.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 70ac2d33ab27..8464c25a2403 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1436,9 +1436,11 @@ xfs_seal_file_space(
xfs_off_t offset,
xfs_off_t len)
{
+ struct xfs_mount *mp = ip->i_mount;
struct inode *inode = VFS_I(ip);
struct address_space *mapping = inode->i_mapping;
int error;
+ struct xfs_trans *tp;

ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));

@@ -1454,6 +1456,10 @@ xfs_seal_file_space(
if (error)
return error;

+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ return error;
+
xfs_ilock(ip, XFS_ILOCK_EXCL);
/*
* Either the size changed after we performed allocation /
@@ -1486,10 +1492,20 @@ xfs_seal_file_space(
if (error < 0)
goto out_unlock;

+ xfs_trans_ijoin(tp, ip, 0);
+ ip->i_d.di_flags2 |= XFS_DIFLAG2_IOMAP_IMMUTABLE;
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ error = xfs_trans_commit(tp);
+ tp = NULL; /* nothing to cancel */
+ if (error)
+ goto out_unlock;
+
inode->i_flags |= S_IOMAP_IMMUTABLE;

out_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (tp)
+ xfs_trans_cancel(tp);

return error;
}
@@ -1500,15 +1516,21 @@ xfs_unseal_file_space(
xfs_off_t offset,
xfs_off_t len)
{
+ struct xfs_mount *mp = ip->i_mount;
struct inode *inode = VFS_I(ip);
struct address_space *mapping = inode->i_mapping;
int error;
+ struct xfs_trans *tp;

ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));

if (offset)
return -EINVAL;

+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ return error;
+
xfs_ilock(ip, XFS_ILOCK_EXCL);
/*
* It does not make sense to unseal less than the full range of
@@ -1527,11 +1549,21 @@ xfs_unseal_file_space(
if (mapping_mapped(mapping))
goto out_unlock;

+ xfs_trans_ijoin(tp, ip, 0);
+ ip->i_d.di_flags2 &= ~XFS_DIFLAG2_IOMAP_IMMUTABLE;
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ error = xfs_trans_commit(tp);
+ tp = NULL; /* nothing to cancel */
+ if (error)
+ goto out_unlock;
+
inode->i_flags &= ~S_IOMAP_IMMUTABLE;
error = 0;

out_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (tp)
+ xfs_trans_cancel(tp);

return error;
}