Commit 9276aad6 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

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: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 68da9f05

mm/shmem.c

+6 −34
Original line number Diff line number Diff line
@@ -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;
@@ -1255,17 +1255,7 @@ 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);

	if (filepage && PageUptodate(filepage))

		goto done;
@@ -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);

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