diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 72 |
1 files changed, 28 insertions, 44 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 100b99c2d50..5d5449f3d41 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -867,13 +867,11 @@ void do_generic_mapping_read(struct address_space *mapping, { struct inode *inode = mapping->host; unsigned long index; - unsigned long end_index; unsigned long offset; unsigned long last_index; unsigned long next_index; unsigned long prev_index; unsigned int prev_offset; - loff_t isize; struct page *cached_page; int error; struct file_ra_state ra = *_ra; @@ -886,27 +884,12 @@ void do_generic_mapping_read(struct address_space *mapping, last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; - isize = i_size_read(inode); - if (!isize) - goto out; - - end_index = (isize - 1) >> PAGE_CACHE_SHIFT; for (;;) { struct page *page; + unsigned long end_index; + loff_t isize; unsigned long nr, ret; - /* nr is the maximum number of bytes to copy from this page */ - nr = PAGE_CACHE_SIZE; - if (index >= end_index) { - if (index > end_index) - goto out; - nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; - if (nr <= offset) { - goto out; - } - } - nr = nr - offset; - cond_resched(); if (index == next_index) next_index = page_cache_readahead(mapping, &ra, filp, @@ -921,6 +904,32 @@ find_page: if (!PageUptodate(page)) goto page_not_up_to_date; page_ok: + /* + * i_size must be checked after we know the page is Uptodate. + * + * Checking i_size after the check allows us to calculate + * the correct value for "nr", which means the zero-filled + * part of the page is not copied back to userspace (unless + * another truncate extends the file - this is desired though). + */ + + isize = i_size_read(inode); + end_index = (isize - 1) >> PAGE_CACHE_SHIFT; + if (unlikely(!isize || index > end_index)) { + page_cache_release(page); + goto out; + } + + /* nr is the maximum number of bytes to copy from this page */ + nr = PAGE_CACHE_SIZE; + if (index == end_index) { + nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; + if (nr <= offset) { + page_cache_release(page); + goto out; + } + } + nr = nr - offset; /* If users can be writing to this page using arbitrary * virtual addresses, take care about potential aliasing @@ -1007,31 +1016,6 @@ readpage: unlock_page(page); } - /* - * i_size must be checked after we have done ->readpage. - * - * Checking i_size after the readpage allows us to calculate - * the correct value for "nr", which means the zero-filled - * part of the page is not copied back to userspace (unless - * another truncate extends the file - this is desired though). - */ - isize = i_size_read(inode); - end_index = (isize - 1) >> PAGE_CACHE_SHIFT; - if (unlikely(!isize || index > end_index)) { - page_cache_release(page); - goto out; - } - - /* nr is the maximum number of bytes to copy from this page */ - nr = PAGE_CACHE_SIZE; - if (index == end_index) { - nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; - if (nr <= offset) { - page_cache_release(page); - goto out; - } - } - nr = nr - offset; goto page_ok; readpage_error: |