Merge branch 'xfs-mmap-lock' into for-next
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 22a5dcb..7efa23e 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1599,13 +1599,6 @@
/* Verify O_DIRECT for ftmp */
if (VFS_I(ip)->i_mapping->nrpages)
return -EINVAL;
-
- /*
- * Don't try to swap extents on mmap()d files because we can't lock
- * out races against page faults safely.
- */
- if (mapping_mapped(VFS_I(ip)->i_mapping))
- return -EBUSY;
return 0;
}
@@ -1633,13 +1626,14 @@
}
/*
- * Lock up the inodes against other IO and truncate to begin with.
- * Then we can ensure the inodes are flushed and have no page cache
- * safely. Once we have done this we can take the ilocks and do the rest
- * of the checks.
+ * Lock the inodes against other IO, page faults and truncate to
+ * begin with. Then we can ensure the inodes are flushed and have no
+ * page cache safely. Once we have done this we can take the ilocks and
+ * do the rest of the checks.
*/
- lock_flags = XFS_IOLOCK_EXCL;
+ lock_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL);
+ xfs_lock_two_inodes(ip, tip, XFS_MMAPLOCK_EXCL);
/* Verify that both files have the same format */
if ((ip->i_d.di_mode & S_IFMT) != (tip->i_d.di_mode & S_IFMT)) {
@@ -1666,8 +1660,16 @@
xfs_trans_cancel(tp, 0);
goto out_unlock;
}
+
+ /*
+ * Lock and join the inodes to the tansaction so that transaction commit
+ * or cancel will unlock the inodes from this point onwards.
+ */
xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);
lock_flags |= XFS_ILOCK_EXCL;
+ xfs_trans_ijoin(tp, ip, lock_flags);
+ xfs_trans_ijoin(tp, tip, lock_flags);
+
/* Verify all data are being swapped */
if (sxp->sx_offset != 0 ||
@@ -1720,9 +1722,6 @@
goto out_trans_cancel;
}
- xfs_trans_ijoin(tp, ip, lock_flags);
- xfs_trans_ijoin(tp, tip, lock_flags);
-
/*
* Before we've swapped the forks, lets set the owners of the forks
* appropriately. We have to do this as we are demand paging the btree
@@ -1856,5 +1855,5 @@
out_trans_cancel:
xfs_trans_cancel(tp, 0);
- goto out_unlock;
+ goto out;
}
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a2e1cb8..b101e80 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -847,6 +847,9 @@
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)
@@ -997,20 +1000,6 @@
}
/*
- * mmap()d file has taken write protection fault and is being made
- * writable. We can set the page state up correctly for a writable
- * page, which means we can do correct delalloc accounting (ENOSPC
- * checking!) and unwritten extent mapping.
- */
-STATIC int
-xfs_vm_page_mkwrite(
- struct vm_area_struct *vma,
- struct vm_fault *vmf)
-{
- return block_page_mkwrite(vma, vmf, xfs_get_blocks);
-}
-
-/*
* This type is designed to indicate the type of offset we would like
* to search from page cache for xfs_seek_hole_data().
*/
@@ -1385,6 +1374,55 @@
}
}
+/*
+ * Locking for serialisation of IO during page faults. This results in a lock
+ * ordering of:
+ *
+ * mmap_sem (MM)
+ * i_mmap_lock (XFS - truncate serialisation)
+ * page_lock (MM)
+ * i_lock (XFS - extent map serialisation)
+ */
+STATIC int
+xfs_filemap_fault(
+ struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
+ int error;
+
+ trace_xfs_filemap_fault(ip);
+
+ xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+ error = filemap_fault(vma, vmf);
+ xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+
+ return error;
+}
+
+/*
+ * mmap()d file has taken write protection fault and is being made writable. We
+ * can set the page state up correctly for a writable page, which means we can
+ * do correct delalloc accounting (ENOSPC checking!) and unwritten extent
+ * mapping.
+ */
+STATIC int
+xfs_filemap_page_mkwrite(
+ struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
+ int error;
+
+ trace_xfs_filemap_page_mkwrite(ip);
+
+ xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+ error = block_page_mkwrite(vma, vmf, xfs_get_blocks);
+ xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+
+ return error;
+}
+
const struct file_operations xfs_file_operations = {
.llseek = xfs_file_llseek,
.read = new_sync_read,
@@ -1417,7 +1455,7 @@
};
static const struct vm_operations_struct xfs_file_vm_ops = {
- .fault = filemap_fault,
+ .fault = xfs_filemap_fault,
.map_pages = filemap_map_pages,
- .page_mkwrite = xfs_vm_page_mkwrite,
+ .page_mkwrite = xfs_filemap_page_mkwrite,
};
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 698da03..5a44f1c 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -117,24 +117,34 @@
}
/*
- * The xfs inode contains 2 locks: a multi-reader lock called the
- * i_iolock and a multi-reader lock called the i_lock. This routine
- * allows either or both of the locks to be obtained.
+ * The xfs inode contains 3 multi-reader locks: the i_iolock the i_mmap_lock and
+ * the i_lock. This routine allows various combinations of the locks to be
+ * obtained.
*
- * The 2 locks should always be ordered so that the IO lock is
- * obtained first in order to prevent deadlock.
+ * The 3 locks should always be ordered so that the IO lock is obtained first,
+ * the mmap lock second and the ilock last in order to prevent deadlock.
*
- * ip -- the inode being locked
- * lock_flags -- this parameter indicates the inode's locks
- * to be locked. It can be:
- * XFS_IOLOCK_SHARED,
- * XFS_IOLOCK_EXCL,
- * XFS_ILOCK_SHARED,
- * XFS_ILOCK_EXCL,
- * XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
- * XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
- * XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
- * XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
+ * Basic locking order:
+ *
+ * i_iolock -> i_mmap_lock -> page_lock -> i_ilock
+ *
+ * mmap_sem locking order:
+ *
+ * i_iolock -> page lock -> mmap_sem
+ * mmap_sem -> i_mmap_lock -> page_lock
+ *
+ * The difference in mmap_sem locking order mean that we cannot hold the
+ * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can
+ * fault in pages during copy in/out (for buffered IO) or require the mmap_sem
+ * in get_user_pages() to map the user pages into the kernel address space for
+ * direct IO. Similarly the i_iolock cannot be taken inside a page fault because
+ * page faults already hold the mmap_sem.
+ *
+ * Hence to serialise fully against both syscall and mmap based IO, we need to
+ * take both the i_iolock and the i_mmap_lock. These locks should *only* be both
+ * taken in places where we need to invalidate the page cache in a race
+ * free manner (e.g. truncate, hole punch and other extent manipulation
+ * functions).
*/
void
xfs_ilock(
@@ -150,6 +160,8 @@
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
+ ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
+ (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
@@ -159,6 +171,11 @@
else if (lock_flags & XFS_IOLOCK_SHARED)
mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
+ if (lock_flags & XFS_MMAPLOCK_EXCL)
+ mrupdate_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
+ else if (lock_flags & XFS_MMAPLOCK_SHARED)
+ mraccess_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
+
if (lock_flags & XFS_ILOCK_EXCL)
mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
else if (lock_flags & XFS_ILOCK_SHARED)
@@ -191,6 +208,8 @@
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
+ ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
+ (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
@@ -202,21 +221,35 @@
if (!mrtryaccess(&ip->i_iolock))
goto out;
}
+
+ if (lock_flags & XFS_MMAPLOCK_EXCL) {
+ if (!mrtryupdate(&ip->i_mmaplock))
+ goto out_undo_iolock;
+ } else if (lock_flags & XFS_MMAPLOCK_SHARED) {
+ if (!mrtryaccess(&ip->i_mmaplock))
+ goto out_undo_iolock;
+ }
+
if (lock_flags & XFS_ILOCK_EXCL) {
if (!mrtryupdate(&ip->i_lock))
- goto out_undo_iolock;
+ goto out_undo_mmaplock;
} else if (lock_flags & XFS_ILOCK_SHARED) {
if (!mrtryaccess(&ip->i_lock))
- goto out_undo_iolock;
+ goto out_undo_mmaplock;
}
return 1;
- out_undo_iolock:
+out_undo_mmaplock:
+ if (lock_flags & XFS_MMAPLOCK_EXCL)
+ mrunlock_excl(&ip->i_mmaplock);
+ else if (lock_flags & XFS_MMAPLOCK_SHARED)
+ mrunlock_shared(&ip->i_mmaplock);
+out_undo_iolock:
if (lock_flags & XFS_IOLOCK_EXCL)
mrunlock_excl(&ip->i_iolock);
else if (lock_flags & XFS_IOLOCK_SHARED)
mrunlock_shared(&ip->i_iolock);
- out:
+out:
return 0;
}
@@ -244,6 +277,8 @@
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
+ ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
+ (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
@@ -254,6 +289,11 @@
else if (lock_flags & XFS_IOLOCK_SHARED)
mrunlock_shared(&ip->i_iolock);
+ if (lock_flags & XFS_MMAPLOCK_EXCL)
+ mrunlock_excl(&ip->i_mmaplock);
+ else if (lock_flags & XFS_MMAPLOCK_SHARED)
+ mrunlock_shared(&ip->i_mmaplock);
+
if (lock_flags & XFS_ILOCK_EXCL)
mrunlock_excl(&ip->i_lock);
else if (lock_flags & XFS_ILOCK_SHARED)
@@ -271,11 +311,14 @@
xfs_inode_t *ip,
uint lock_flags)
{
- ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
- ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
+ ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL));
+ ASSERT((lock_flags &
+ ~(XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
if (lock_flags & XFS_ILOCK_EXCL)
mrdemote(&ip->i_lock);
+ if (lock_flags & XFS_MMAPLOCK_EXCL)
+ mrdemote(&ip->i_mmaplock);
if (lock_flags & XFS_IOLOCK_EXCL)
mrdemote(&ip->i_iolock);
@@ -294,6 +337,12 @@
return rwsem_is_locked(&ip->i_lock.mr_lock);
}
+ if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
+ if (!(lock_flags & XFS_MMAPLOCK_SHARED))
+ return !!ip->i_mmaplock.mr_writer;
+ return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
+ }
+
if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
if (!(lock_flags & XFS_IOLOCK_SHARED))
return !!ip->i_iolock.mr_writer;
@@ -314,14 +363,27 @@
#endif
/*
- * Bump the subclass so xfs_lock_inodes() acquires each lock with
- * a different value
+ * Bump the subclass so xfs_lock_inodes() acquires each lock with a different
+ * value. This shouldn't be called for page fault locking, but we also need to
+ * ensure we don't overrun the number of lockdep subclasses for the iolock or
+ * mmaplock as that is limited to 12 by the mmap lock lockdep annotations.
*/
static inline int
xfs_lock_inumorder(int lock_mode, int subclass)
{
- if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
+ if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
+ ASSERT(subclass + XFS_LOCK_INUMORDER <
+ (1 << (XFS_MMAPLOCK_SHIFT - XFS_IOLOCK_SHIFT)));
lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_IOLOCK_SHIFT;
+ }
+
+ if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) {
+ ASSERT(subclass + XFS_LOCK_INUMORDER <
+ (1 << (XFS_ILOCK_SHIFT - XFS_MMAPLOCK_SHIFT)));
+ lock_mode |= (subclass + XFS_LOCK_INUMORDER) <<
+ XFS_MMAPLOCK_SHIFT;
+ }
+
if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))
lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_ILOCK_SHIFT;
@@ -440,10 +502,10 @@
}
/*
- * xfs_lock_two_inodes() can only be used to lock one type of lock
- * at a time - the iolock or the ilock, but not both at once. If
- * we lock both at once, lockdep will report false positives saying
- * we have violated locking orders.
+ * xfs_lock_two_inodes() can only be used to lock one type of lock at a time -
+ * the iolock, the mmaplock or the ilock, but not more than one at a time. If we
+ * lock more than one at a time, lockdep will report false positives saying we
+ * have violated locking orders.
*/
void
xfs_lock_two_inodes(
@@ -455,8 +517,12 @@
int attempts = 0;
xfs_log_item_t *lp;
- if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
- ASSERT((lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) == 0);
+ if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
+ ASSERT(!(lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
+ ASSERT(!(lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
+ } else if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL))
+ ASSERT(!(lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
+
ASSERT(ip0->i_ino != ip1->i_ino);
if (ip0->i_ino > ip1->i_ino) {
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index c73b63d..8f22d20 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -56,6 +56,7 @@
struct xfs_inode_log_item *i_itemp; /* logging information */
mrlock_t i_lock; /* inode lock */
mrlock_t i_iolock; /* inode IO lock */
+ mrlock_t i_mmaplock; /* inode mmap IO lock */
atomic_t i_pincount; /* inode pin count */
spinlock_t i_flags_lock; /* inode i_flags lock */
/* Miscellaneous state. */
@@ -263,15 +264,20 @@
#define XFS_IOLOCK_SHARED (1<<1)
#define XFS_ILOCK_EXCL (1<<2)
#define XFS_ILOCK_SHARED (1<<3)
+#define XFS_MMAPLOCK_EXCL (1<<4)
+#define XFS_MMAPLOCK_SHARED (1<<5)
#define XFS_LOCK_MASK (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED \
- | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)
+ | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED \
+ | XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED)
#define XFS_LOCK_FLAGS \
{ XFS_IOLOCK_EXCL, "IOLOCK_EXCL" }, \
{ XFS_IOLOCK_SHARED, "IOLOCK_SHARED" }, \
{ XFS_ILOCK_EXCL, "ILOCK_EXCL" }, \
- { XFS_ILOCK_SHARED, "ILOCK_SHARED" }
+ { XFS_ILOCK_SHARED, "ILOCK_SHARED" }, \
+ { XFS_MMAPLOCK_EXCL, "MMAPLOCK_EXCL" }, \
+ { XFS_MMAPLOCK_SHARED, "MMAPLOCK_SHARED" }
/*
@@ -302,17 +308,26 @@
#define XFS_IOLOCK_SHIFT 16
#define XFS_IOLOCK_PARENT (XFS_LOCK_PARENT << XFS_IOLOCK_SHIFT)
+#define XFS_MMAPLOCK_SHIFT 20
+
#define XFS_ILOCK_SHIFT 24
#define XFS_ILOCK_PARENT (XFS_LOCK_PARENT << XFS_ILOCK_SHIFT)
#define XFS_ILOCK_RTBITMAP (XFS_LOCK_RTBITMAP << XFS_ILOCK_SHIFT)
#define XFS_ILOCK_RTSUM (XFS_LOCK_RTSUM << XFS_ILOCK_SHIFT)
-#define XFS_IOLOCK_DEP_MASK 0x00ff0000
+#define XFS_IOLOCK_DEP_MASK 0x000f0000
+#define XFS_MMAPLOCK_DEP_MASK 0x00f00000
#define XFS_ILOCK_DEP_MASK 0xff000000
-#define XFS_LOCK_DEP_MASK (XFS_IOLOCK_DEP_MASK | XFS_ILOCK_DEP_MASK)
+#define XFS_LOCK_DEP_MASK (XFS_IOLOCK_DEP_MASK | \
+ XFS_MMAPLOCK_DEP_MASK | \
+ XFS_ILOCK_DEP_MASK)
-#define XFS_IOLOCK_DEP(flags) (((flags) & XFS_IOLOCK_DEP_MASK) >> XFS_IOLOCK_SHIFT)
-#define XFS_ILOCK_DEP(flags) (((flags) & XFS_ILOCK_DEP_MASK) >> XFS_ILOCK_SHIFT)
+#define XFS_IOLOCK_DEP(flags) (((flags) & XFS_IOLOCK_DEP_MASK) \
+ >> XFS_IOLOCK_SHIFT)
+#define XFS_MMAPLOCK_DEP(flags) (((flags) & XFS_MMAPLOCK_DEP_MASK) \
+ >> XFS_MMAPLOCK_SHIFT)
+#define XFS_ILOCK_DEP(flags) (((flags) & XFS_ILOCK_DEP_MASK) \
+ >> XFS_ILOCK_SHIFT)
/*
* For multiple groups support: if S_ISGID bit is set in the parent
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index ac4feae..4ee44dd 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -631,7 +631,7 @@
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 @@
if (error)
goto out_unlock;
+ xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
+ iolock |= XFS_MMAPLOCK_EXCL;
+
switch (bf->l_whence) {
case 0: /*SEEK_SET*/
break;
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 3ccc28e..8b9e688 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -771,6 +771,7 @@
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);
@@ -834,55 +835,27 @@
inode_dio_wait(inode);
/*
- * Do all the page cache truncate work outside the transaction context
- * as the "lock" order is page lock->log space reservation. i.e.
- * locking pages inside the transaction can ABBA deadlock with
- * writeback. We have to do the VFS inode size update before we truncate
- * the pagecache, however, to avoid racing with page faults beyond the
- * new EOF they are not serialised against truncate operations except by
- * page locks and size updates.
+ * We've already locked out new page faults, so now we can safely remove
+ * pages from the page cache knowing they won't get refaulted until we
+ * drop the XFS_MMAP_EXCL lock after the extent manipulations are
+ * complete. The truncate_setsize() call also cleans partial EOF page
+ * PTEs on extending truncates and hence ensures sub-page block size
+ * filesystems are correctly handled, too.
*
- * Hence we are in a situation where a truncate can fail with ENOMEM
- * from xfs_trans_reserve(), but having already truncated the in-memory
- * version of the file (i.e. made user visible changes). There's not
- * much we can do about this, except to hope that the caller sees ENOMEM
- * and retries the truncate operation.
+ * We have to do all the page cache truncate work outside the
+ * transaction context as the "lock" order is page lock->log space
+ * reservation as defined by extent allocation in the writeback path.
+ * Hence a truncate can fail with ENOMEM from xfs_trans_reserve(), but
+ * having already truncated the in-memory version of the file (i.e. made
+ * user visible changes). There's not much we can do about this, except
+ * to hope that the caller sees ENOMEM and retries the truncate
+ * operation.
*/
error = block_truncate_page(inode->i_mapping, newsize, xfs_get_blocks);
if (error)
return error;
truncate_setsize(inode, newsize);
- /*
- * The "we can't serialise against page faults" pain gets worse.
- *
- * If the file is mapped then we have to clean the page at the old EOF
- * when extending the file. Extending the file can expose changes the
- * underlying page mapping (e.g. from beyond EOF to a hole or
- * unwritten), and so on the next attempt to write to that page we need
- * to remap it for write. i.e. we need .page_mkwrite() to be called.
- * Hence we need to clean the page to clean the pte and so a new write
- * fault will be triggered appropriately.
- *
- * If we do it before we change the inode size, then we can race with a
- * page fault that maps the page with exactly the same problem. If we do
- * it after we change the file size, then a new page fault can come in
- * and allocate space before we've run the rest of the truncate
- * transaction. That's kinda grotesque, but it's better than have data
- * over a hole, and so that's the lesser evil that has been chosen here.
- *
- * The real solution, however, is to have some mechanism for locking out
- * page faults while a truncate is in progress.
- */
- if (newsize > oldsize && mapping_mapped(VFS_I(ip)->i_mapping)) {
- error = filemap_write_and_wait_range(
- VFS_I(ip)->i_mapping,
- round_down(oldsize, PAGE_CACHE_SIZE),
- round_up(oldsize, PAGE_CACHE_SIZE) - 1);
- if (error)
- return error;
- }
-
tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_SIZE);
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
if (error)
@@ -981,8 +954,12 @@
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);
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index f32ad64..3ad0b17 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -966,6 +966,8 @@
atomic_set(&ip->i_pincount, 0);
spin_lock_init(&ip->i_flags_lock);
+ mrlock_init(&ip->i_mmaplock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
+ "xfsino", ip->i_ino);
mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
"xfsino", ip->i_ino);
}
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 51372e3..b1e059b 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -685,6 +685,9 @@
DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
+DEFINE_INODE_EVENT(xfs_filemap_fault);
+DEFINE_INODE_EVENT(xfs_filemap_page_mkwrite);
+
DECLARE_EVENT_CLASS(xfs_iref_class,
TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),
TP_ARGS(ip, caller_ip),
