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authorLinus Torvalds <torvalds@linux-foundation.org>2014-10-20 09:50:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-20 09:50:11 -0700
commitc2661b806092d8ea2dccb7b02b65776555e0ee47 (patch)
treeebc73fa58706e5a0a79235953c532ac6c6e2b539 /mm/truncate.c
parentf114040e3ea6e07372334ade75d1ee0775c355e1 (diff)
parent813d32f91333e4c33d5a19b67167c4bae42dae75 (diff)
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o: "A large number of cleanups and bug fixes, with some (minor) journal optimizations" [ This got sent to me before -rc1, but was stuck in my spam folder. - Linus ] * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (67 commits) ext4: check s_chksum_driver when looking for bg csum presence ext4: move error report out of atomic context in ext4_init_block_bitmap() ext4: Replace open coded mdata csum feature to helper function ext4: delete useless comments about ext4_move_extents ext4: fix reservation overflow in ext4_da_write_begin ext4: add ext4_iget_normal() which is to be used for dir tree lookups ext4: don't orphan or truncate the boot loader inode ext4: grab missed write_count for EXT4_IOC_SWAP_BOOT ext4: optimize block allocation on grow indepth ext4: get rid of code duplication ext4: fix over-defensive complaint after journal abort ext4: fix return value of ext4_do_update_inode ext4: fix mmap data corruption when blocksize < pagesize vfs: fix data corruption when blocksize < pagesize for mmaped data ext4: fold ext4_nojournal_sops into ext4_sops ext4: support freezing ext2 (nojournal) file systems ext4: fold ext4_sync_fs_nojournal() into ext4_sync_fs() ext4: don't check quota format when there are no quota files jbd2: simplify calling convention around __jbd2_journal_clean_checkpoint_list jbd2: avoid pointless scanning of checkpoint lists ...
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 96d167372d89..261eaf6e5a19 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -20,6 +20,7 @@
#include <linux/buffer_head.h> /* grr. try_to_release_page,
do_invalidatepage */
#include <linux/cleancache.h>
+#include <linux/rmap.h>
#include "internal.h"
static void clear_exceptional_entry(struct address_space *mapping,
@@ -719,12 +720,68 @@ EXPORT_SYMBOL(truncate_pagecache);
*/
void truncate_setsize(struct inode *inode, loff_t newsize)
{
+ loff_t oldsize = inode->i_size;
+
i_size_write(inode, newsize);
+ if (newsize > oldsize)
+ pagecache_isize_extended(inode, oldsize, newsize);
truncate_pagecache(inode, newsize);
}
EXPORT_SYMBOL(truncate_setsize);
/**
+ * pagecache_isize_extended - update pagecache after extension of i_size
+ * @inode: inode for which i_size was extended
+ * @from: original inode size
+ * @to: new inode size
+ *
+ * Handle extension of inode size either caused by extending truncate or by
+ * write starting after current i_size. We mark the page straddling current
+ * i_size RO so that page_mkwrite() is called on the nearest write access to
+ * the page. This way filesystem can be sure that page_mkwrite() is called on
+ * the page before user writes to the page via mmap after the i_size has been
+ * changed.
+ *
+ * The function must be called after i_size is updated so that page fault
+ * coming after we unlock the page will already see the new i_size.
+ * The function must be called while we still hold i_mutex - this not only
+ * makes sure i_size is stable but also that userspace cannot observe new
+ * i_size value before we are prepared to store mmap writes at new inode size.
+ */
+void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
+{
+ int bsize = 1 << inode->i_blkbits;
+ loff_t rounded_from;
+ struct page *page;
+ pgoff_t index;
+
+ WARN_ON(!mutex_is_locked(&inode->i_mutex));
+ WARN_ON(to > inode->i_size);
+
+ if (from >= to || bsize == PAGE_CACHE_SIZE)
+ return;
+ /* Page straddling @from will not have any hole block created? */
+ rounded_from = round_up(from, bsize);
+ if (to <= rounded_from || !(rounded_from & (PAGE_CACHE_SIZE - 1)))
+ return;
+
+ index = from >> PAGE_CACHE_SHIFT;
+ page = find_lock_page(inode->i_mapping, index);
+ /* Page not cached? Nothing to do */
+ if (!page)
+ return;
+ /*
+ * See clear_page_dirty_for_io() for details why set_page_dirty()
+ * is needed.
+ */
+ if (page_mkclean(page))
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+}
+EXPORT_SYMBOL(pagecache_isize_extended);
+
+/**
* truncate_pagecache_range - unmap and remove pagecache that is hole-punched
* @inode: inode
* @lstart: offset of beginning of hole