The patch titled
Subject: tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)
has been added to the -mm tree. Its filename is
tmpfs-support-seek_data-and-seek_hole-reprise.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)
Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE") to
reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"), with
the intervening additional arg to generic_file_llseek_size().
In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
SEEK_DATA and SEEK_HOLE support; and a good case has now been made for it
on tmpfs, so let's join the party.
It's quite easy for tmpfs to scan the radix_tree to support llseek's new
SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
on my mind (in particular, the !PageUptodate-ness of pages fallocated but
still unwritten).
[akpm@xxxxxxxxxxxxxxxxxxxx: fix warning with CONFIG_TMPFS=n]
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jaegeuk Hanse <jaegeuk.hanse@xxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Cc: Jeff liu <jeff.liu@xxxxxxxxxx>
Cc: Paul Eggert <eggert@xxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger@xxxxxxxxx>
Cc: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxxxx>
Cc: Sunil Mushran <sunil.mushran@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 91 insertions(+), 1 deletion(-)
diff -puN mm/shmem.c~tmpfs-support-seek_data-and-seek_hole-reprise mm/shmem.c
--- a/mm/shmem.c~tmpfs-support-seek_data-and-seek_hole-reprise
+++ a/mm/shmem.c
@@ -1709,6 +1709,96 @@ static ssize_t shmem_file_splice_read(st
return error;
}
+/*
+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ */
+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
+ pgoff_t index, pgoff_t end, int origin)
+{
+ struct page *page;
+ struct pagevec pvec;
+ pgoff_t indices[PAGEVEC_SIZE];
+ bool done = false;
+ int i;
+
+ pagevec_init(&pvec, 0);
+ pvec.nr = 1; /* start small: we may be there already */
+ while (!done) {
+ pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+ pvec.nr, pvec.pages, indices);
+ if (!pvec.nr) {
+ if (origin == SEEK_DATA)
+ index = end;
+ break;
+ }
+ for (i = 0; i < pvec.nr; i++, index++) {
+ if (index < indices[i]) {
+ if (origin == SEEK_HOLE) {
+ done = true;
+ break;
+ }
+ index = indices[i];
+ }
+ page = pvec.pages[i];
+ if (page && !radix_tree_exceptional_entry(page)) {
+ if (!PageUptodate(page))
+ page = NULL;
+ }
+ if (index >= end ||
+ (page && origin == SEEK_DATA) ||
+ (!page && origin == SEEK_HOLE)) {
+ done = true;
+ break;
+ }
+ }
+ shmem_deswap_pagevec(&pvec);
+ pagevec_release(&pvec);
+ pvec.nr = PAGEVEC_SIZE;
+ cond_resched();
+ }
+ return index;
+}
+
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
+{
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ pgoff_t start, end;
+ loff_t new_offset;
+
+ if (origin != SEEK_DATA && origin != SEEK_HOLE)
+ return generic_file_llseek_size(file, offset, origin,
+ MAX_LFS_FILESIZE, i_size_read(inode));
+ mutex_lock(&inode->i_mutex);
+ /* We're holding i_mutex so we can access i_size directly */
+
+ if (offset < 0)
+ offset = -EINVAL;
+ else if (offset >= inode->i_size)
+ offset = -ENXIO;
+ else {
+ start = offset >> PAGE_CACHE_SHIFT;
+ end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ new_offset = shmem_seek_hole_data(mapping, start, end, origin);
+ new_offset <<= PAGE_CACHE_SHIFT;
+ if (new_offset > offset) {
+ if (new_offset < inode->i_size)
+ offset = new_offset;
+ else if (origin == SEEK_DATA)
+ offset = -ENXIO;
+ else
+ offset = inode->i_size;
+ }
+ }
+
+ if (offset >= 0 && offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ mutex_unlock(&inode->i_mutex);
+ return offset;
+}
+
static long shmem_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
@@ -2580,7 +2670,7 @@ static const struct address_space_operat
static const struct file_operations shmem_file_operations = {
.mmap = shmem_mmap,
#ifdef CONFIG_TMPFS
- .llseek = generic_file_llseek,
+ .llseek = shmem_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = shmem_file_aio_read,
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
linux-next.patch
mm-add-comment-on-storage-key-dirty-bit-semantics.patch
mm-refactor-reinsert-of-swap_info-in-sys_swapoff.patch
mm-do-not-call-frontswap_init-during-swapoff.patch
mm-augment-vma-rbtree-with-rb_subtree_gap.patch
mm-augment-vma-rbtree-with-rb_subtree_gap-ensure-safe-rb_subtree_gap-update-when-inserting-new-vma.patch
mm-augment-vma-rbtree-with-rb_subtree_gap-ensure-safe-rb_subtree_gap-update-when-removing-vma.patch
mm-augment-vma-rbtree-with-rb_subtree_gap--debug-code-to-verify-rb_subtree_gap-updates-are-safe.patch
mm-check-rb_subtree_gap-correctness.patch
mm-check-rb_subtree_gap-correctness-fix.patch
mm-rearrange-vm_area_struct-for-fewer-cache-misses.patch
mm-vm_unmapped_area-lookup-function.patch
mm-use-vm_unmapped_area-on-x86_64-architecture.patch
mm-fix-cache-coloring-on-x86_64-architecture.patch
mm-use-vm_unmapped_area-in-hugetlbfs.patch
mm-use-vm_unmapped_area-in-hugetlbfs-on-i386-architecture.patch
mm-use-vm_unmapped_area-in-hugetlbfs-on-i386-architecture-fix.patch
mm-use-vm_unmapped_area-on-mips-architecture.patch
mm-use-vm_unmapped_area-on-mips-architecture-fix.patch
mm-use-vm_unmapped_area-on-arm-architecture.patch
mm-use-vm_unmapped_area-on-arm-architecture-fix.patch
mm-use-vm_unmapped_area-on-sh-architecture.patch
mm-use-vm_unmapped_area-on-sh-architecture-fix.patch
mm-use-vm_unmapped_area-on-sparc32-architecture.patch
mm-use-vm_unmapped_area-in-hugetlbfs-on-tile-architecture.patch
mm-use-vm_unmapped_area-on-sparc64-architecture.patch
mm-use-vm_unmapped_area-on-sparc64-architecture-fix.patch
mm-use-vm_unmapped_area-in-hugetlbfs-on-sparc64-architecture.patch
mm-trace-filemap-add-and-del.patch
tmpfs-support-seek_data-and-seek_hole-reprise.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead-fix.patch
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