From 9276aad6c898dbcc31d095f2934dedd5cbb2e93e Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 25 Jul 2011 17:12:34 -0700 Subject: [PATCH] tmpfs: remove_shmem_readpage Remove that pernicious shmem_readpage() at last: the things we needed it for (splice, loop, sendfile, i915 GEM) are now fully taken care of by shmem_file_splice_read() and shmem_read_mapping_page_gfp(). This removal clears the way for a simpler shmem_getpage_gfp(), since page is never passed in; but leave most of that cleanup until after. sys_readahead() and sys_fadvise(POSIX_FADV_WILLNEED) will now EINVAL, instead of unexpectedly trying to read ahead on tmpfs: if that proves to be an issue for someone, then we can either arrange for them to return success instead, or try to implement async readahead on tmpfs. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 40 ++++++---------------------------------- 1 file changed, 6 insertions(+), 34 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index f6c94ba87808..ff6713a2579e 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1246,7 +1246,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx, struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo; - struct page *filepage = *pagep; + struct page *filepage; struct page *swappage; struct page *prealloc_page = NULL; swp_entry_t *entry; @@ -1255,18 +1255,8 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx, if (idx >= SHMEM_MAX_INDEX) return -EFBIG; - - /* - * Normally, filepage is NULL on entry, and either found - * uptodate immediately, or allocated and zeroed, or read - * in under swappage, which is then assigned to filepage. - * But shmem_readpage (required for splice) passes in a locked - * filepage, which may be found not uptodate by other callers - * too, and may need to be copied from the swappage read in. - */ repeat: - if (!filepage) - filepage = find_lock_page(mapping, idx); + filepage = find_lock_page(mapping, idx); if (filepage && PageUptodate(filepage)) goto done; if (!filepage) { @@ -1513,8 +1503,7 @@ nospace: * Perhaps the page was brought in from swap between find_lock_page * and taking info->lock? We allow for that at add_to_page_cache_lru, * but must also avoid reporting a spurious ENOSPC while working on a - * full tmpfs. (When filepage has been passed in to shmem_getpage, it - * is already in page cache, which prevents this race from occurring.) + * full tmpfs. */ if (!filepage) { struct page *page = find_get_page(mapping, idx); @@ -1527,7 +1516,7 @@ nospace: spin_unlock(&info->lock); error = -ENOSPC; failed: - if (*pagep != filepage) { + if (filepage) { unlock_page(filepage); page_cache_release(filepage); } @@ -1673,19 +1662,6 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode static const struct inode_operations shmem_symlink_inode_operations; static const struct inode_operations shmem_symlink_inline_operations; -/* - * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; - * but providing them allows a tmpfs file to be used for splice, sendfile, and - * below the loop driver, in the generic fashion that many filesystems support. - */ -static int shmem_readpage(struct file *file, struct page *page) -{ - struct inode *inode = page->mapping->host; - int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); - unlock_page(page); - return error; -} - static int shmem_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, @@ -1693,7 +1669,6 @@ shmem_write_begin(struct file *file, struct address_space *mapping, { struct inode *inode = mapping->host; pgoff_t index = pos >> PAGE_CACHE_SHIFT; - *pagep = NULL; return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); } @@ -1893,7 +1868,6 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, error = 0; while (spd.nr_pages < nr_pages) { - page = NULL; error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); if (error) break; @@ -1916,7 +1890,6 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, page = spd.pages[page_nr]; if (!PageUptodate(page) || page->mapping != mapping) { - page = NULL; error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); if (error) @@ -2125,7 +2098,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s int error; int len; struct inode *inode; - struct page *page = NULL; + struct page *page; char *kaddr; struct shmem_inode_info *info; @@ -2803,7 +2776,6 @@ static const struct address_space_operations shmem_aops = { .writepage = shmem_writepage, .set_page_dirty = __set_page_dirty_no_writeback, #ifdef CONFIG_TMPFS - .readpage = shmem_readpage, .write_begin = shmem_write_begin, .write_end = shmem_write_end, #endif @@ -3175,7 +3147,7 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, { #ifdef CONFIG_SHMEM struct inode *inode = mapping->host; - struct page *page = NULL; + struct page *page; int error; BUG_ON(mapping->a_ops != &shmem_aops); -- 2.20.1