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authorHugh Dickins <hughd@google.com>2011-06-27 16:18:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-27 18:00:12 -0700
commit94c1e62df4494b79782cb9c7279f827212d1de70 (patch)
tree43013fb403e592c535e6a7770be105b635ac9b63 /mm/truncate.c
parent072441e21ddcd1140606b7d4ef6eab579a86b0b3 (diff)
tmpfs: take control of its truncate_range
2.6.35's new truncate convention gave tmpfs the opportunity to control its file truncation, no longer enforced from outside by vmtruncate(). We shall want to build upon that, to handle pagecache and swap together. Slightly redefine the ->truncate_range interface: let it now be called between the unmap_mapping_range()s, with the filesystem responsible for doing the truncate_inode_pages_range() from it - just as the filesystem is nowadays responsible for doing that from its ->setattr. Let's rename shmem_notify_change() to shmem_setattr(). Instead of calling the generic truncate_setsize(), bring that code in so we can call shmem_truncate_range() - which will later be updated to perform its own variant of truncate_inode_pages_range(). Remove the punch_hole unmap_mapping_range() from shmem_truncate_range(): now that the COW's unmap_mapping_range() comes after ->truncate_range, there is no need to call it a third time. Export shmem_truncate_range() and add it to the list in shmem_fs.h, so that i915_gem_object_truncate() can call it explicitly in future; get this patch in first, then update drm/i915 once this is available (until then, i915 will just be doing the truncate_inode_pages() twice). Though introduced five years ago, no other filesystem is implementing ->truncate_range, and its only other user is madvise(,,MADV_REMOVE): we expect to convert it to fallocate(,FALLOC_FL_PUNCH_HOLE,,) shortly, whereupon ->truncate_range can be removed from inode_operations - shmem_truncate_range() will help i915 across that transition too. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 5b4c3a4847e..29a9b8a5a31 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -619,9 +619,9 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
mutex_lock(&inode->i_mutex);
down_write(&inode->i_alloc_sem);
unmap_mapping_range(mapping, offset, (end - offset), 1);
- truncate_inode_pages_range(mapping, offset, end);
- unmap_mapping_range(mapping, offset, (end - offset), 1);
inode->i_op->truncate_range(inode, offset, end);
+ /* unmap again to remove racily COWed private pages */
+ unmap_mapping_range(mapping, offset, (end - offset), 1);
up_write(&inode->i_alloc_sem);
mutex_unlock(&inode->i_mutex);