From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 6 Oct 2007 21:46:33 +0100 (BST) From: Hugh Dickins Subject: [PATCH 5/7] shmem_getpage return page locked In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Nick Piggin , linux-mm@kvack.org List-ID: In the new aops, write_begin is supposed to return the page locked: though I've seen no ill effects, that's been overlooked in the case of shmem_write_begin, and should be fixed. Then shmem_write_end must unlock the page: do so _after_ updating i_size, as we found to be important in other filesystems (though since shmem pages don't go the usual writeback route, they never suffered from that corruption). For shmem_write_begin to return the page locked, we need shmem_getpage to return the page locked in SGP_WRITE case as well as SGP_CACHE case: let's simplify the interface and return it locked even when SGP_READ. Signed-off-by: Hugh Dickins --- mm/shmem.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) --- patch4/mm/shmem.c 2007-10-04 19:24:39.000000000 +0100 +++ patch5/mm/shmem.c 2007-10-04 19:24:41.000000000 +0100 @@ -729,6 +729,8 @@ static int shmem_notify_change(struct de (void) shmem_getpage(inode, attr->ia_size>>PAGE_CACHE_SHIFT, &page, SGP_READ, NULL); + if (page) + unlock_page(page); } /* * Reset SHMEM_PAGEIN flag so that shmem_truncate can @@ -1270,12 +1272,7 @@ repeat: SetPageUptodate(filepage); } done: - if (*pagep != filepage) { - *pagep = filepage; - if (sgp != SGP_CACHE) - unlock_page(filepage); - - } + *pagep = filepage; return 0; failed: @@ -1453,12 +1450,13 @@ shmem_write_end(struct file *file, struc { struct inode *inode = mapping->host; + if (pos + copied > inode->i_size) + i_size_write(inode, pos + copied); + + unlock_page(page); set_page_dirty(page); page_cache_release(page); - if (pos+copied > inode->i_size) - i_size_write(inode, pos+copied); - return copied; } @@ -1513,6 +1511,7 @@ shmem_file_write(struct file *file, cons if (err) break; + unlock_page(page); left = bytes; if (PageHighMem(page)) { volatile unsigned char dummy; @@ -1594,6 +1593,8 @@ static void do_shmem_file_read(struct fi desc->error = 0; break; } + if (page) + unlock_page(page); /* * We must evaluate after, since reads (unlike writes) @@ -1883,6 +1884,7 @@ static int shmem_symlink(struct inode *d iput(inode); return error; } + unlock_page(page); inode->i_op = &shmem_symlink_inode_operations; kaddr = kmap_atomic(page, KM_USER0); memcpy(kaddr, symname, len); @@ -1910,6 +1912,8 @@ static void *shmem_follow_link(struct de struct page *page = NULL; int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); + if (page) + unlock_page(page); return page; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org