From 915bae9ebe41e52d71ad8b06d50e4ab26189f964 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 6 Dec 2006 20:34:07 -0800 Subject: [PATCH] [PATCH] swsusp: use partition device and offset to identify swap areas The Linux kernel handles swap files almost in the same way as it handles swap partitions and there are only two differences between these two types of swap areas: (1) swap files need not be contiguous, (2) the header of a swap file is not in the first block of the partition that holds it. From the swsusp's point of view (1) is not a problem, because it is already taken care of by the swap-handling code, but (2) has to be taken into consideration. In principle the location of a swap file's header may be determined with the help of appropriate filesystem driver. Unfortunately, however, it requires the filesystem holding the swap file to be mounted, and if this filesystem is journaled, it cannot be mounted during a resume from disk. For this reason we need some other means by which swap areas can be identified. For example, to identify a swap area we can use the partition that holds the area and the offset from the beginning of this partition at which the swap header is located. The following patch allows swsusp to identify swap areas this way. It changes swap_type_of() so that it takes an additional argument representing an offset of the swap header within the partition represented by its first argument. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 2 +- kernel/power/swap.c | 2 +- kernel/power/user.c | 5 +++-- mm/swapfile.c | 38 ++++++++++++++++++++++++++------------ 4 files changed, 31 insertions(+), 16 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 89f8a39773bf..d51e35e4e168 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -247,7 +247,7 @@ extern int swap_duplicate(swp_entry_t); extern int valid_swaphandles(swp_entry_t, unsigned long *); extern void swap_free(swp_entry_t); extern void free_swap_and_cache(swp_entry_t); -extern int swap_type_of(dev_t); +extern int swap_type_of(dev_t, sector_t); extern unsigned int count_swap_pages(int, int); extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t); extern struct swap_info_struct *get_swap_info_struct(unsigned); diff --git a/kernel/power/swap.c b/kernel/power/swap.c index 1a3b0dd2c3fc..7b10da16389e 100644 --- a/kernel/power/swap.c +++ b/kernel/power/swap.c @@ -74,7 +74,7 @@ static int mark_swapfiles(swp_entry_t start) static int swsusp_swap_check(void) /* This is called before saving image */ { - int res = swap_type_of(swsusp_resume_device); + int res = swap_type_of(swsusp_resume_device, 0); if (res >= 0) { root_swap = res; diff --git a/kernel/power/user.c b/kernel/power/user.c index 4c24ca5d62e3..a327b18a5ffd 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -55,7 +55,8 @@ static int snapshot_open(struct inode *inode, struct file *filp) filp->private_data = data; memset(&data->handle, 0, sizeof(struct snapshot_handle)); if ((filp->f_flags & O_ACCMODE) == O_RDONLY) { - data->swap = swsusp_resume_device ? swap_type_of(swsusp_resume_device) : -1; + data->swap = swsusp_resume_device ? + swap_type_of(swsusp_resume_device, 0) : -1; data->mode = O_RDONLY; } else { data->swap = -1; @@ -265,7 +266,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp, * so we need to recode them */ if (old_decode_dev(arg)) { - data->swap = swap_type_of(old_decode_dev(arg)); + data->swap = swap_type_of(old_decode_dev(arg), 0); if (data->swap < 0) error = -ENODEV; } else { diff --git a/mm/swapfile.c b/mm/swapfile.c index f315131db006..2bfacbac0f4c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -427,34 +427,48 @@ void free_swap_and_cache(swp_entry_t entry) #ifdef CONFIG_SOFTWARE_SUSPEND /* - * Find the swap type that corresponds to given device (if any) + * Find the swap type that corresponds to given device (if any). * - * This is needed for software suspend and is done in such a way that inode - * aliasing is allowed. + * @offset - number of the PAGE_SIZE-sized block of the device, starting + * from 0, in which the swap header is expected to be located. + * + * This is needed for the suspend to disk (aka swsusp). */ -int swap_type_of(dev_t device) +int swap_type_of(dev_t device, sector_t offset) { + struct block_device *bdev = NULL; int i; + if (device) + bdev = bdget(device); + spin_lock(&swap_lock); for (i = 0; i < nr_swapfiles; i++) { - struct inode *inode; + struct swap_info_struct *sis = swap_info + i; - if (!(swap_info[i].flags & SWP_WRITEOK)) + if (!(sis->flags & SWP_WRITEOK)) continue; - if (!device) { + if (!bdev) { spin_unlock(&swap_lock); return i; } - inode = swap_info[i].swap_file->f_dentry->d_inode; - if (S_ISBLK(inode->i_mode) && - device == MKDEV(imajor(inode), iminor(inode))) { - spin_unlock(&swap_lock); - return i; + if (bdev == sis->bdev) { + struct swap_extent *se; + + se = list_entry(sis->extent_list.next, + struct swap_extent, list); + if (se->start_block == offset) { + spin_unlock(&swap_lock); + bdput(bdev); + return i; + } } } spin_unlock(&swap_lock); + if (bdev) + bdput(bdev); + return -ENODEV; } -- 2.20.1