The patch titled
shmem_file_write is redundant
has been added to the -mm tree. Its filename is
shmem_file_write-is-redundant.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: shmem_file_write is redundant
From: Hugh Dickins <hugh@xxxxxxxxxxx>
With the old aops, writing to a tmpfs file had to use its own special method:
the generic method would pass in a fresh page to prepare_write when the right
page was there in swapcache - which was inefficient to handle, even once we'd
concocted the code to handle it.
With the new aops, the generic method uses shmem_write_end, which lets
shmem_getpage find the right page: so now abandon shmem_file_write in favour
of the generic method. Yes, that does do several things that tmpfs hasn't
really needed (notably balance_dirty_pages_ratelimited, which ramfs also
calls); but more use of common code is preferable.
Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 109 +--------------------------------------------------
1 file changed, 3 insertions(+), 106 deletions(-)
diff -puN mm/shmem.c~shmem_file_write-is-redundant mm/shmem.c
--- a/mm/shmem.c~shmem_file_write-is-redundant
+++ a/mm/shmem.c
@@ -1091,7 +1091,7 @@ static int shmem_getpage(struct inode *i
* 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 and shmem_write_begin pass in a locked
+ * 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.
*/
@@ -1460,110 +1460,6 @@ shmem_write_end(struct file *file, struc
return copied;
}
-static ssize_t
-shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
-{
- struct inode *inode = file->f_path.dentry->d_inode;
- loff_t pos;
- unsigned long written;
- ssize_t err;
-
- if ((ssize_t) count < 0)
- return -EINVAL;
-
- if (!access_ok(VERIFY_READ, buf, count))
- return -EFAULT;
-
- mutex_lock(&inode->i_mutex);
-
- pos = *ppos;
- written = 0;
-
- err = generic_write_checks(file, &pos, &count, 0);
- if (err || !count)
- goto out;
-
- err = remove_suid(file->f_path.dentry);
- if (err)
- goto out;
-
- inode->i_ctime = inode->i_mtime = CURRENT_TIME;
-
- do {
- struct page *page = NULL;
- unsigned long bytes, index, offset;
- char *kaddr;
- int left;
-
- offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
- index = pos >> PAGE_CACHE_SHIFT;
- bytes = PAGE_CACHE_SIZE - offset;
- if (bytes > count)
- bytes = count;
-
- /*
- * We don't hold page lock across copy from user -
- * what would it guard against? - so no deadlock here.
- * But it still may be a good idea to prefault below.
- */
-
- err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
- if (err)
- break;
-
- unlock_page(page);
- left = bytes;
- if (PageHighMem(page)) {
- volatile unsigned char dummy;
- __get_user(dummy, buf);
- __get_user(dummy, buf + bytes - 1);
-
- kaddr = kmap_atomic(page, KM_USER0);
- left = __copy_from_user_inatomic(kaddr + offset,
- buf, bytes);
- kunmap_atomic(kaddr, KM_USER0);
- }
- if (left) {
- kaddr = kmap(page);
- left = __copy_from_user(kaddr + offset, buf, bytes);
- kunmap(page);
- }
-
- written += bytes;
- count -= bytes;
- pos += bytes;
- buf += bytes;
- if (pos > inode->i_size)
- i_size_write(inode, pos);
-
- flush_dcache_page(page);
- set_page_dirty(page);
- mark_page_accessed(page);
- page_cache_release(page);
-
- if (left) {
- pos -= left;
- written -= left;
- err = -EFAULT;
- break;
- }
-
- /*
- * Our dirty pages are not counted in nr_dirty,
- * and we do not attempt to balance dirty pages.
- */
-
- cond_resched();
- } while (count);
-
- *ppos = pos;
- if (written)
- err = written;
-out:
- mutex_unlock(&inode->i_mutex);
- return err;
-}
-
static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
struct inode *inode = filp->f_path.dentry->d_inode;
@@ -2338,7 +2234,8 @@ static const struct file_operations shme
#ifdef CONFIG_TMPFS
.llseek = generic_file_llseek,
.read = shmem_file_read,
- .write = shmem_file_write,
+ .write = do_sync_write,
+ .aio_write = generic_file_aio_write,
.fsync = simple_sync_file,
.splice_read = generic_file_splice_read,
.splice_write = generic_file_splice_write,
_
Patches currently in -mm which might be from hugh@xxxxxxxxxxx are
origin.patch
exportfs-add-fid-type.patch
exportfs-add-new-methods.patch
shmem-new-export-ops.patch
exportfs-remove-old-methods.patch
exportfs-make-struct-export_operations-const.patch
exportfs-update-documentation.patch
fix-mprotect-vma_wants_writenotify-prot.patch
swapin_readahead-excise-numa-bogosity.patch
swapin_readahead-move-and-rearrange-args.patch
swapin-needs-gfp_mask-for-loop-on-tmpfs.patch
shmem-sgp_quick-and-sgp_fault-redundant.patch
shmem_getpage-return-page-locked.patch
shmem_file_write-is-redundant.patch
swapin-fix-valid_swaphandles-defect.patch
memory-controller-memory-accounting-v7.patch
prio_tree-debugging-patch.patch
-
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