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 <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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parent
68da9f0557
commit
9276aad6c8
38
mm/shmem.c
38
mm/shmem.c
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@ -1246,7 +1246,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx,
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struct address_space *mapping = inode->i_mapping;
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struct shmem_inode_info *info = SHMEM_I(inode);
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struct shmem_sb_info *sbinfo;
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struct page *filepage = *pagep;
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struct page *filepage;
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struct page *swappage;
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struct page *prealloc_page = NULL;
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swp_entry_t *entry;
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@ -1255,17 +1255,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx,
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if (idx >= SHMEM_MAX_INDEX)
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return -EFBIG;
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/*
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* Normally, filepage is NULL on entry, and either found
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* uptodate immediately, or allocated and zeroed, or read
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* in under swappage, which is then assigned to filepage.
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* But shmem_readpage (required for splice) passes in a locked
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* filepage, which may be found not uptodate by other callers
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* too, and may need to be copied from the swappage read in.
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*/
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repeat:
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if (!filepage)
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filepage = find_lock_page(mapping, idx);
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if (filepage && PageUptodate(filepage))
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goto done;
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@ -1513,8 +1503,7 @@ nospace:
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* Perhaps the page was brought in from swap between find_lock_page
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* and taking info->lock? We allow for that at add_to_page_cache_lru,
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* but must also avoid reporting a spurious ENOSPC while working on a
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* full tmpfs. (When filepage has been passed in to shmem_getpage, it
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* is already in page cache, which prevents this race from occurring.)
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* full tmpfs.
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*/
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if (!filepage) {
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struct page *page = find_get_page(mapping, idx);
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@ -1527,7 +1516,7 @@ nospace:
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spin_unlock(&info->lock);
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error = -ENOSPC;
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failed:
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if (*pagep != filepage) {
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if (filepage) {
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unlock_page(filepage);
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page_cache_release(filepage);
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}
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@ -1673,19 +1662,6 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
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static const struct inode_operations shmem_symlink_inode_operations;
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static const struct inode_operations shmem_symlink_inline_operations;
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/*
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* Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
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* but providing them allows a tmpfs file to be used for splice, sendfile, and
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* below the loop driver, in the generic fashion that many filesystems support.
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*/
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static int shmem_readpage(struct file *file, struct page *page)
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{
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struct inode *inode = page->mapping->host;
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int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
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unlock_page(page);
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return error;
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}
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static int
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shmem_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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@ -1693,7 +1669,6 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
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{
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struct inode *inode = mapping->host;
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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*pagep = NULL;
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return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
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}
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@ -1893,7 +1868,6 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
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error = 0;
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while (spd.nr_pages < nr_pages) {
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page = NULL;
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error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
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if (error)
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break;
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@ -1916,7 +1890,6 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
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page = spd.pages[page_nr];
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if (!PageUptodate(page) || page->mapping != mapping) {
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page = NULL;
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error = shmem_getpage(inode, index, &page,
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SGP_CACHE, NULL);
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if (error)
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@ -2125,7 +2098,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
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int error;
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int len;
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struct inode *inode;
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struct page *page = NULL;
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struct page *page;
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char *kaddr;
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struct shmem_inode_info *info;
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@ -2803,7 +2776,6 @@ static const struct address_space_operations shmem_aops = {
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.writepage = shmem_writepage,
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.set_page_dirty = __set_page_dirty_no_writeback,
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#ifdef CONFIG_TMPFS
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.readpage = shmem_readpage,
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.write_begin = shmem_write_begin,
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.write_end = shmem_write_end,
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#endif
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@ -3175,7 +3147,7 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
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{
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#ifdef CONFIG_SHMEM
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struct inode *inode = mapping->host;
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struct page *page = NULL;
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struct page *page;
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int error;
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BUG_ON(mapping->a_ops != &shmem_aops);
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