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xfs: move helpers that lock and unlock two inodes against userspace IO

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Move the double-inode locking helpers to xfs_inode.c since they're not
specific to reflink.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
This commit is contained in:
Darrick J. Wong 2020-06-29 14:47:20 -07:00
parent 10b4bd6c9c
commit e2aaee9cd3
5 changed files with 99 additions and 97 deletions
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2
fs/xfs/xfs_file.c
View file

@ -1065,7 +1065,7 @@ xfs_file_remap_range(
if (mp->m_flags & XFS_MOUNT_WSYNC)
xfs_log_force_inode(dest);
out_unlock:
xfs_reflink_remap_unlock(src, dest);
xfs_iunlock2_io_mmap(src, dest);
if (ret)
trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
return remapped > 0 ? remapped : ret;

93
fs/xfs/xfs_inode.c
View file

@ -3881,3 +3881,96 @@ xfs_log_force_inode(
return 0;
return xfs_log_force_lsn(ip->i_mount, lsn, XFS_LOG_SYNC, NULL);
}
/*
* Grab the exclusive iolock for a data copy from src to dest, making sure to
* abide vfs locking order (lowest pointer value goes first) and breaking the
* layout leases before proceeding. The loop is needed because we cannot call
* the blocking break_layout() with the iolocks held, and therefore have to
* back out both locks.
*/
static int
xfs_iolock_two_inodes_and_break_layout(
struct inode *src,
struct inode *dest)
{
int error;
if (src > dest)
swap(src, dest);
retry:
/* Wait to break both inodes' layouts before we start locking. */
error = break_layout(src, true);
if (error)
return error;
if (src != dest) {
error = break_layout(dest, true);
if (error)
return error;
}
/* Lock one inode and make sure nobody got in and leased it. */
inode_lock(src);
error = break_layout(src, false);
if (error) {
inode_unlock(src);
if (error == -EWOULDBLOCK)
goto retry;
return error;
}
if (src == dest)
return 0;
/* Lock the other inode and make sure nobody got in and leased it. */
inode_lock_nested(dest, I_MUTEX_NONDIR2);
error = break_layout(dest, false);
if (error) {
inode_unlock(src);
inode_unlock(dest);
if (error == -EWOULDBLOCK)
goto retry;
return error;
}
return 0;
}
/*
* Lock two inodes so that userspace cannot initiate I/O via file syscalls or
* mmap activity.
*/
int
xfs_ilock2_io_mmap(
struct xfs_inode *ip1,
struct xfs_inode *ip2)
{
int ret;
ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
if (ret)
return ret;
if (ip1 == ip2)
xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
else
xfs_lock_two_inodes(ip1, XFS_MMAPLOCK_EXCL,
ip2, XFS_MMAPLOCK_EXCL);
return 0;
}
/* Unlock both inodes to allow IO and mmap activity. */
void
xfs_iunlock2_io_mmap(
struct xfs_inode *ip1,
struct xfs_inode *ip2)
{
bool same_inode = (ip1 == ip2);
xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
if (!same_inode)
xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
inode_unlock(VFS_I(ip2));
if (!same_inode)
inode_unlock(VFS_I(ip1));
}

3
fs/xfs/xfs_inode.h
View file

@ -499,4 +499,7 @@ void xfs_iunlink_destroy(struct xfs_perag *pag);
void xfs_end_io(struct work_struct *work);
int xfs_ilock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
void xfs_iunlock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
#endif /* __XFS_INODE_H__ */

97
fs/xfs/xfs_reflink.c
View file

@ -1229,99 +1229,6 @@ xfs_reflink_remap_blocks(
return error;
}
/*
* Grab the exclusive iolock for a data copy from src to dest, making sure to
* abide vfs locking order (lowest pointer value goes first) and breaking the
* layout leases before proceeding. The loop is needed because we cannot call
* the blocking break_layout() with the iolocks held, and therefore have to
* back out both locks.
*/
static int
xfs_iolock_two_inodes_and_break_layout(
struct inode *src,
struct inode *dest)
{
int error;
if (src > dest)
swap(src, dest);
retry:
/* Wait to break both inodes' layouts before we start locking. */
error = break_layout(src, true);
if (error)
return error;
if (src != dest) {
error = break_layout(dest, true);
if (error)
return error;
}
/* Lock one inode and make sure nobody got in and leased it. */
inode_lock(src);
error = break_layout(src, false);
if (error) {
inode_unlock(src);
if (error == -EWOULDBLOCK)
goto retry;
return error;
}
if (src == dest)
return 0;
/* Lock the other inode and make sure nobody got in and leased it. */
inode_lock_nested(dest, I_MUTEX_NONDIR2);
error = break_layout(dest, false);
if (error) {
inode_unlock(src);
inode_unlock(dest);
if (error == -EWOULDBLOCK)
goto retry;
return error;
}
return 0;
}
/*
* Lock two files so that userspace cannot initiate I/O via file syscalls or
* mmap activity.
*/
static int
xfs_reflink_remap_lock(
struct xfs_inode *ip1,
struct xfs_inode *ip2)
{
int ret;
ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
if (ret)
return ret;
if (ip1 == ip2)
xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
else
xfs_lock_two_inodes(ip1, XFS_MMAPLOCK_EXCL,
ip2, XFS_MMAPLOCK_EXCL);
return 0;
}
/* Unlock both files to allow IO and mmap activity. */
void
xfs_reflink_remap_unlock(
struct xfs_inode *ip1,
struct xfs_inode *ip2)
{
bool same_inode = (ip1 == ip2);
xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
if (!same_inode)
xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
inode_unlock(VFS_I(ip2));
if (!same_inode)
inode_unlock(VFS_I(ip1));
}
/*
* If we're reflinking to a point past the destination file's EOF, we must
* zero any speculative post-EOF preallocations that sit between the old EOF
@ -1387,7 +1294,7 @@ xfs_reflink_remap_prep(
int ret;
/* Lock both files against IO */
ret = xfs_reflink_remap_lock(src, dest);
ret = xfs_ilock2_io_mmap(src, dest);
if (ret)
return ret;
@ -1440,7 +1347,7 @@ xfs_reflink_remap_prep(
return 0;
out_unlock:
xfs_reflink_remap_unlock(src, dest);
xfs_iunlock2_io_mmap(src, dest);
return ret;
}

1
fs/xfs/xfs_reflink.h
View file

@ -56,6 +56,5 @@ extern int xfs_reflink_remap_blocks(struct xfs_inode *src, loff_t pos_in,
loff_t *remapped);
extern int xfs_reflink_update_dest(struct xfs_inode *dest, xfs_off_t newlen,
xfs_extlen_t cowextsize, unsigned int remap_flags);
extern void xfs_reflink_remap_unlock(struct xfs_inode *ip1, struct xfs_inode *ip2);
#endif /* __XFS_REFLINK_H */