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xfs: take i_mmap_lock on extent manipulation operations 

Now we have the i_mmap_lock being held across the page fault IO
path, we now add extent manipulation operation exclusion by adding
the lock to the paths that directly modify extent maps. This
includes truncate, hole punching and other fallocate based
operations. The operations will now take both the i_iolock and the
i_mmaplock in exclusive mode, thereby ensuring that all IO and page
faults block without holding any page locks while the extent
manipulation is in progress.

This gives us the lock order during truncate of i_iolock ->
i_mmaplock -> page_lock -> i_lock, hence providing the same
lock order as the iolock provides the normal IO path without
involving the mmap_sem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Dave Chinner 2015-02-23 21:45:32 +11:00 committed by Dave Chinner
parent 075a924d45
commit e8e9ad42c1
3 changed files with 13 additions and 2 deletions
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3
fs/xfs/xfs_file.c
View File

@ -841,6 +841,9 @@ xfs_file_fallocate(
if (error)
goto out_unlock;
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
iolock |= XFS_MMAPLOCK_EXCL;
if (mode & FALLOC_FL_PUNCH_HOLE) {
error = xfs_free_file_space(ip, offset, len);
if (error)

5
fs/xfs/xfs_ioctl.c
View File

@ -631,7 +631,7 @@ xfs_ioc_space(
if (filp->f_flags & O_DSYNC)
flags |= XFS_PREALLOC_SYNC;
if (ioflags & XFS_IO_INVIS)
if (ioflags & XFS_IO_INVIS)
flags |= XFS_PREALLOC_INVISIBLE;
error = mnt_want_write_file(filp);
@ -643,6 +643,9 @@ xfs_ioc_space(
if (error)
goto out_unlock;
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
iolock |= XFS_MMAPLOCK_EXCL;
switch (bf->l_whence) {
case 0: /*SEEK_SET*/
break;

7
fs/xfs/xfs_iops.c
View File

@ -765,6 +765,7 @@ xfs_setattr_size(
return error;
ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
ASSERT(S_ISREG(ip->i_d.di_mode));
ASSERT((iattr->ia_valid & (ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET|
ATTR_MTIME_SET|ATTR_KILL_PRIV|ATTR_TIMES_SET)) == 0);
@ -984,8 +985,12 @@ xfs_vn_setattr(
xfs_ilock(ip, iolock);
error = xfs_break_layouts(dentry->d_inode, &iolock);
if (!error)
if (!error) {
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
iolock |= XFS_MMAPLOCK_EXCL;
error = xfs_setattr_size(ip, iattr);
}
xfs_iunlock(ip, iolock);
} else {
error = xfs_setattr_nonsize(ip, iattr, 0);