mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-24 17:59:32 +00:00
![OGAWA Hirofumi](/assets/img/avatar_default.png)
When a writeback_control's `start' and `end' fields are used to indicate a one-byte-range starting at file offset zero, the required values of .start=0,.end=0 mean that the ->writepages() implementation has no way of telling that it is being asked to perform a range request. Because we're currently overloading (start == 0 && end == 0) to mean "this is not a write-a-range request". To make all this sane, the patch changes range of writeback_control. So caller does: If it is calling ->writepages() to write pages, it sets range (range_start/end or range_cyclic) always. And if range_cyclic is true, ->writepages() thinks the range is cyclic, otherwise it just uses range_start and range_end. This patch does, - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h -1 is usually ok for range_end (type is long long). But, if someone did, range_end += val; range_end is "val - 1" u64val = range_end >> bits; u64val is "~(0ULL)" or something, they are wrong. So, this adds LLONG_MAX to avoid nasty things, and uses LLONG_MAX for range_end. - All callers of ->writepages() sets range_start/end or range_cyclic. - Fix updates of ->writeback_index. It seems already bit strange. If it starts at 0 and ended by check of nr_to_write, this last index may reduce chance to scan end of file. So, this updates ->writeback_index only if range_cyclic is true or whole-file is scanned. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Nathan Scott <nathans@sgi.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Steven French <sfrench@us.ibm.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
164 lines
4.4 KiB
C
164 lines
4.4 KiB
C
/*
|
|
* High-level sync()-related operations
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/file.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/module.h>
|
|
#include <linux/writeback.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/linkage.h>
|
|
#include <linux/pagemap.h>
|
|
|
|
#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
|
|
SYNC_FILE_RANGE_WAIT_AFTER)
|
|
|
|
/*
|
|
* sys_sync_file_range() permits finely controlled syncing over a segment of
|
|
* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
|
|
* zero then sys_sync_file_range() will operate from offset out to EOF.
|
|
*
|
|
* The flag bits are:
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
|
|
* before performing the write.
|
|
*
|
|
* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
|
|
* range which are not presently under writeback.
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
|
|
* after performing the write.
|
|
*
|
|
* Useful combinations of the flag bits are:
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
|
|
* in the range which were dirty on entry to sys_sync_file_range() are placed
|
|
* under writeout. This is a start-write-for-data-integrity operation.
|
|
*
|
|
* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
|
|
* are not presently under writeout. This is an asynchronous flush-to-disk
|
|
* operation. Not suitable for data integrity operations.
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
|
|
* completion of writeout of all pages in the range. This will be used after an
|
|
* earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
|
|
* for that operation to complete and to return the result.
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
|
|
* a traditional sync() operation. This is a write-for-data-integrity operation
|
|
* which will ensure that all pages in the range which were dirty on entry to
|
|
* sys_sync_file_range() are committed to disk.
|
|
*
|
|
*
|
|
* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
|
|
* I/O errors or ENOSPC conditions and will return those to the caller, after
|
|
* clearing the EIO and ENOSPC flags in the address_space.
|
|
*
|
|
* It should be noted that none of these operations write out the file's
|
|
* metadata. So unless the application is strictly performing overwrites of
|
|
* already-instantiated disk blocks, there are no guarantees here that the data
|
|
* will be available after a crash.
|
|
*/
|
|
asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
|
|
unsigned int flags)
|
|
{
|
|
int ret;
|
|
struct file *file;
|
|
loff_t endbyte; /* inclusive */
|
|
int fput_needed;
|
|
umode_t i_mode;
|
|
|
|
ret = -EINVAL;
|
|
if (flags & ~VALID_FLAGS)
|
|
goto out;
|
|
|
|
endbyte = offset + nbytes;
|
|
|
|
if ((s64)offset < 0)
|
|
goto out;
|
|
if ((s64)endbyte < 0)
|
|
goto out;
|
|
if (endbyte < offset)
|
|
goto out;
|
|
|
|
if (sizeof(pgoff_t) == 4) {
|
|
if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
|
|
/*
|
|
* The range starts outside a 32 bit machine's
|
|
* pagecache addressing capabilities. Let it "succeed"
|
|
*/
|
|
ret = 0;
|
|
goto out;
|
|
}
|
|
if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
|
|
/*
|
|
* Out to EOF
|
|
*/
|
|
nbytes = 0;
|
|
}
|
|
}
|
|
|
|
if (nbytes == 0)
|
|
endbyte = LLONG_MAX;
|
|
else
|
|
endbyte--; /* inclusive */
|
|
|
|
ret = -EBADF;
|
|
file = fget_light(fd, &fput_needed);
|
|
if (!file)
|
|
goto out;
|
|
|
|
i_mode = file->f_dentry->d_inode->i_mode;
|
|
ret = -ESPIPE;
|
|
if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
|
|
!S_ISLNK(i_mode))
|
|
goto out_put;
|
|
|
|
ret = do_sync_file_range(file, offset, endbyte, flags);
|
|
out_put:
|
|
fput_light(file, fput_needed);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* `endbyte' is inclusive
|
|
*/
|
|
int do_sync_file_range(struct file *file, loff_t offset, loff_t endbyte,
|
|
unsigned int flags)
|
|
{
|
|
int ret;
|
|
struct address_space *mapping;
|
|
|
|
mapping = file->f_mapping;
|
|
if (!mapping) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
ret = 0;
|
|
if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
|
|
ret = wait_on_page_writeback_range(mapping,
|
|
offset >> PAGE_CACHE_SHIFT,
|
|
endbyte >> PAGE_CACHE_SHIFT);
|
|
if (ret < 0)
|
|
goto out;
|
|
}
|
|
|
|
if (flags & SYNC_FILE_RANGE_WRITE) {
|
|
ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
|
|
WB_SYNC_NONE);
|
|
if (ret < 0)
|
|
goto out;
|
|
}
|
|
|
|
if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
|
|
ret = wait_on_page_writeback_range(mapping,
|
|
offset >> PAGE_CACHE_SHIFT,
|
|
endbyte >> PAGE_CACHE_SHIFT);
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(do_sync_file_range);
|