fallocate should be a file operation

Currently all filesystems except XFS implement fallocate asynchronously,
while XFS forced a commit.  Both of these are suboptimal - in case of O_SYNC
I/O we really want our allocation on disk, especially for the !KEEP_SIZE
case where we actually grow the file with user-visible zeroes.  On the
other hand always commiting the transaction is a bad idea for fast-path
uses of fallocate like for example in recent Samba versions.   Given
that block allocation is a data plane operation anyway change it from
an inode operation to a file operation so that we have the file structure
available that lets us check for O_SYNC.

This also includes moving the code around for a few of the filesystems,
and remove the already unnedded S_ISDIR checks given that we only wire
up fallocate for regular files.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 258 insertions, 258 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index fca6689..7cfdcb9 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -19,6 +19,8 @@
 #include <linux/fs.h>
 #include <linux/gfs2_ondisk.h>
 #include <linux/ext2_fs.h>
+#include <linux/falloc.h>
+#include <linux/swap.h>
 #include <linux/crc32.h>
 #include <linux/writeback.h>
 #include <asm/uaccess.h>
@@ -610,6 +612,260 @@ static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	return generic_file_aio_write(iocb, iov, nr_segs, pos);
 }
 
+static void empty_write_end(struct page *page, unsigned from,
+			   unsigned to)
+{
+	struct gfs2_inode *ip = GFS2_I(page->mapping->host);
+
+	page_zero_new_buffers(page, from, to);
+	flush_dcache_page(page);
+	mark_page_accessed(page);
+
+	if (!gfs2_is_writeback(ip))
+		gfs2_page_add_databufs(ip, page, from, to);
+
+	block_commit_write(page, from, to);
+}
+
+static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
+{
+	unsigned start, end, next;
+	struct buffer_head *bh, *head;
+	int error;
+
+	if (!page_has_buffers(page)) {
+		error = __block_write_begin(page, from, to - from, gfs2_block_map);
+		if (unlikely(error))
+			return error;
+
+		empty_write_end(page, from, to);
+		return 0;
+	}
+
+	bh = head = page_buffers(page);
+	next = end = 0;
+	while (next < from) {
+		next += bh->b_size;
+		bh = bh->b_this_page;
+	}
+	start = next;
+	do {
+		next += bh->b_size;
+		if (buffer_mapped(bh)) {
+			if (end) {
+				error = __block_write_begin(page, start, end - start,
+							    gfs2_block_map);
+				if (unlikely(error))
+					return error;
+				empty_write_end(page, start, end);
+				end = 0;
+			}
+			start = next;
+		}
+		else
+			end = next;
+		bh = bh->b_this_page;
+	} while (next < to);
+
+	if (end) {
+		error = __block_write_begin(page, start, end - start, gfs2_block_map);
+		if (unlikely(error))
+			return error;
+		empty_write_end(page, start, end);
+	}
+
+	return 0;
+}
+
+static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
+			   int mode)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct buffer_head *dibh;
+	int error;
+	u64 start = offset >> PAGE_CACHE_SHIFT;
+	unsigned int start_offset = offset & ~PAGE_CACHE_MASK;
+	u64 end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
+	pgoff_t curr;
+	struct page *page;
+	unsigned int end_offset = (offset + len) & ~PAGE_CACHE_MASK;
+	unsigned int from, to;
+
+	if (!end_offset)
+		end_offset = PAGE_CACHE_SIZE;
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (unlikely(error))
+		goto out;
+
+	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
+
+	if (gfs2_is_stuffed(ip)) {
+		error = gfs2_unstuff_dinode(ip, NULL);
+		if (unlikely(error))
+			goto out;
+	}
+
+	curr = start;
+	offset = start << PAGE_CACHE_SHIFT;
+	from = start_offset;
+	to = PAGE_CACHE_SIZE;
+	while (curr <= end) {
+		page = grab_cache_page_write_begin(inode->i_mapping, curr,
+						   AOP_FLAG_NOFS);
+		if (unlikely(!page)) {
+			error = -ENOMEM;
+			goto out;
+		}
+
+		if (curr == end)
+			to = end_offset;
+		error = write_empty_blocks(page, from, to);
+		if (!error && offset + to > inode->i_size &&
+		    !(mode & FALLOC_FL_KEEP_SIZE)) {
+			i_size_write(inode, offset + to);
+		}
+		unlock_page(page);
+		page_cache_release(page);
+		if (error)
+			goto out;
+		curr++;
+		offset += PAGE_CACHE_SIZE;
+		from = 0;
+	}
+
+	gfs2_dinode_out(ip, dibh->b_data);
+	mark_inode_dirty(inode);
+
+	brelse(dibh);
+
+out:
+	return error;
+}
+
+static void calc_max_reserv(struct gfs2_inode *ip, loff_t max, loff_t *len,
+			    unsigned int *data_blocks, unsigned int *ind_blocks)
+{
+	const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	unsigned int max_blocks = ip->i_alloc->al_rgd->rd_free_clone;
+	unsigned int tmp, max_data = max_blocks - 3 * (sdp->sd_max_height - 1);
+
+	for (tmp = max_data; tmp > sdp->sd_diptrs;) {
+		tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
+		max_data -= tmp;
+	}
+	/* This calculation isn't the exact reverse of gfs2_write_calc_reserve,
+	   so it might end up with fewer data blocks */
+	if (max_data <= *data_blocks)
+		return;
+	*data_blocks = max_data;
+	*ind_blocks = max_blocks - max_data;
+	*len = ((loff_t)max_data - 3) << sdp->sd_sb.sb_bsize_shift;
+	if (*len > max) {
+		*len = max;
+		gfs2_write_calc_reserv(ip, max, data_blocks, ind_blocks);
+	}
+}
+
+static long gfs2_fallocate(struct file *file, int mode, loff_t offset,
+			   loff_t len)
+{
+	struct inode *inode = file->f_path.dentry->d_inode;
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct gfs2_inode *ip = GFS2_I(inode);
+	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
+	loff_t bytes, max_bytes;
+	struct gfs2_alloc *al;
+	int error;
+	loff_t next = (offset + len - 1) >> sdp->sd_sb.sb_bsize_shift;
+	next = (next + 1) << sdp->sd_sb.sb_bsize_shift;
+
+	/* We only support the FALLOC_FL_KEEP_SIZE mode */
+	if (mode & ~FALLOC_FL_KEEP_SIZE)
+		return -EOPNOTSUPP;
+
+	offset = (offset >> sdp->sd_sb.sb_bsize_shift) <<
+		 sdp->sd_sb.sb_bsize_shift;
+
+	len = next - offset;
+	bytes = sdp->sd_max_rg_data * sdp->sd_sb.sb_bsize / 2;
+	if (!bytes)
+		bytes = UINT_MAX;
+
+	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
+	error = gfs2_glock_nq(&ip->i_gh);
+	if (unlikely(error))
+		goto out_uninit;
+
+	if (!gfs2_write_alloc_required(ip, offset, len))
+		goto out_unlock;
+
+	while (len > 0) {
+		if (len < bytes)
+			bytes = len;
+		al = gfs2_alloc_get(ip);
+		if (!al) {
+			error = -ENOMEM;
+			goto out_unlock;
+		}
+
+		error = gfs2_quota_lock_check(ip);
+		if (error)
+			goto out_alloc_put;
+
+retry:
+		gfs2_write_calc_reserv(ip, bytes, &data_blocks, &ind_blocks);
+
+		al->al_requested = data_blocks + ind_blocks;
+		error = gfs2_inplace_reserve(ip);
+		if (error) {
+			if (error == -ENOSPC && bytes > sdp->sd_sb.sb_bsize) {
+				bytes >>= 1;
+				goto retry;
+			}
+			goto out_qunlock;
+		}
+		max_bytes = bytes;
+		calc_max_reserv(ip, len, &max_bytes, &data_blocks, &ind_blocks);
+		al->al_requested = data_blocks + ind_blocks;
+
+		rblocks = RES_DINODE + ind_blocks + RES_STATFS + RES_QUOTA +
+			  RES_RG_HDR + gfs2_rg_blocks(al);
+		if (gfs2_is_jdata(ip))
+			rblocks += data_blocks ? data_blocks : 1;
+
+		error = gfs2_trans_begin(sdp, rblocks,
+					 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
+		if (error)
+			goto out_trans_fail;
+
+		error = fallocate_chunk(inode, offset, max_bytes, mode);
+		gfs2_trans_end(sdp);
+
+		if (error)
+			goto out_trans_fail;
+
+		len -= max_bytes;
+		offset += max_bytes;
+		gfs2_inplace_release(ip);
+		gfs2_quota_unlock(ip);
+		gfs2_alloc_put(ip);
+	}
+	goto out_unlock;
+
+out_trans_fail:
+	gfs2_inplace_release(ip);
+out_qunlock:
+	gfs2_quota_unlock(ip);
+out_alloc_put:
+	gfs2_alloc_put(ip);
+out_unlock:
+	gfs2_glock_dq(&ip->i_gh);
+out_uninit:
+	gfs2_holder_uninit(&ip->i_gh);
+	return error;
+}
+
 #ifdef CONFIG_GFS2_FS_LOCKING_DLM
 
 /**
@@ -765,6 +1021,7 @@ const struct file_operations gfs2_file_fops = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= generic_file_splice_write,
 	.setlease	= gfs2_setlease,
+	.fallocate	= gfs2_fallocate,
 };
 
 const struct file_operations gfs2_dir_fops = {
@@ -794,6 +1051,7 @@ const struct file_operations gfs2_file_fops_nolock = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= generic_file_splice_write,
 	.setlease	= generic_setlease,
+	.fallocate	= gfs2_fallocate,
 };
 
 const struct file_operations gfs2_dir_fops_nolock = {
diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c
index c09528c..d8b26ac 100644
--- a/fs/gfs2/ops_inode.c
+++ b/fs/gfs2/ops_inode.c
@@ -18,8 +18,6 @@
 #include <linux/gfs2_ondisk.h>
 #include <linux/crc32.h>
 #include <linux/fiemap.h>
-#include <linux/swap.h>
-#include <linux/falloc.h>
 #include <asm/uaccess.h>
 
 #include "gfs2.h"
@@ -1257,261 +1255,6 @@ static int gfs2_removexattr(struct dentry *dentry, const char *name)
 	return ret;
 }
 
-static void empty_write_end(struct page *page, unsigned from,
-			   unsigned to)
-{
-	struct gfs2_inode *ip = GFS2_I(page->mapping->host);
-
-	page_zero_new_buffers(page, from, to);
-	flush_dcache_page(page);
-	mark_page_accessed(page);
-
-	if (!gfs2_is_writeback(ip))
-		gfs2_page_add_databufs(ip, page, from, to);
-
-	block_commit_write(page, from, to);
-}
-
-
-static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
-{
-	unsigned start, end, next;
-	struct buffer_head *bh, *head;
-	int error;
-
-	if (!page_has_buffers(page)) {
-		error = __block_write_begin(page, from, to - from, gfs2_block_map);
-		if (unlikely(error))
-			return error;
-
-		empty_write_end(page, from, to);
-		return 0;
-	}
-
-	bh = head = page_buffers(page);
-	next = end = 0;
-	while (next < from) {
-		next += bh->b_size;
-		bh = bh->b_this_page;
-	}
-	start = next;
-	do {
-		next += bh->b_size;
-		if (buffer_mapped(bh)) {
-			if (end) {
-				error = __block_write_begin(page, start, end - start,
-							    gfs2_block_map);
-				if (unlikely(error))
-					return error;
-				empty_write_end(page, start, end);
-				end = 0;
-			}
-			start = next;
-		}
-		else
-			end = next;
-		bh = bh->b_this_page;
-	} while (next < to);
-
-	if (end) {
-		error = __block_write_begin(page, start, end - start, gfs2_block_map);
-		if (unlikely(error))
-			return error;
-		empty_write_end(page, start, end);
-	}
-
-	return 0;
-}
-
-static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
-			   int mode)
-{
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct buffer_head *dibh;
-	int error;
-	u64 start = offset >> PAGE_CACHE_SHIFT;
-	unsigned int start_offset = offset & ~PAGE_CACHE_MASK;
-	u64 end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
-	pgoff_t curr;
-	struct page *page;
-	unsigned int end_offset = (offset + len) & ~PAGE_CACHE_MASK;
-	unsigned int from, to;
-
-	if (!end_offset)
-		end_offset = PAGE_CACHE_SIZE;
-
-	error = gfs2_meta_inode_buffer(ip, &dibh);
-	if (unlikely(error))
-		goto out;
-
-	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
-
-	if (gfs2_is_stuffed(ip)) {
-		error = gfs2_unstuff_dinode(ip, NULL);
-		if (unlikely(error))
-			goto out;
-	}
-
-	curr = start;
-	offset = start << PAGE_CACHE_SHIFT;
-	from = start_offset;
-	to = PAGE_CACHE_SIZE;
-	while (curr <= end) {
-		page = grab_cache_page_write_begin(inode->i_mapping, curr,
-						   AOP_FLAG_NOFS);
-		if (unlikely(!page)) {
-			error = -ENOMEM;
-			goto out;
-		}
-
-		if (curr == end)
-			to = end_offset;
-		error = write_empty_blocks(page, from, to);
-		if (!error && offset + to > inode->i_size &&
-		    !(mode & FALLOC_FL_KEEP_SIZE)) {
-			i_size_write(inode, offset + to);
-		}
-		unlock_page(page);
-		page_cache_release(page);
-		if (error)
-			goto out;
-		curr++;
-		offset += PAGE_CACHE_SIZE;
-		from = 0;
-	}
-
-	gfs2_dinode_out(ip, dibh->b_data);
-	mark_inode_dirty(inode);
-
-	brelse(dibh);
-
-out:
-	return error;
-}
-
-static void calc_max_reserv(struct gfs2_inode *ip, loff_t max, loff_t *len,
-			    unsigned int *data_blocks, unsigned int *ind_blocks)
-{
-	const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
-	unsigned int max_blocks = ip->i_alloc->al_rgd->rd_free_clone;
-	unsigned int tmp, max_data = max_blocks - 3 * (sdp->sd_max_height - 1);
-
-	for (tmp = max_data; tmp > sdp->sd_diptrs;) {
-		tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
-		max_data -= tmp;
-	}
-	/* This calculation isn't the exact reverse of gfs2_write_calc_reserve,
-	   so it might end up with fewer data blocks */
-	if (max_data <= *data_blocks)
-		return;
-	*data_blocks = max_data;
-	*ind_blocks = max_blocks - max_data;
-	*len = ((loff_t)max_data - 3) << sdp->sd_sb.sb_bsize_shift;
-	if (*len > max) {
-		*len = max;
-		gfs2_write_calc_reserv(ip, max, data_blocks, ind_blocks);
-	}
-}
-
-static long gfs2_fallocate(struct inode *inode, int mode, loff_t offset,
-			   loff_t len)
-{
-	struct gfs2_sbd *sdp = GFS2_SB(inode);
-	struct gfs2_inode *ip = GFS2_I(inode);
-	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
-	loff_t bytes, max_bytes;
-	struct gfs2_alloc *al;
-	int error;
-	loff_t next = (offset + len - 1) >> sdp->sd_sb.sb_bsize_shift;
-	next = (next + 1) << sdp->sd_sb.sb_bsize_shift;
-
-	/* We only support the FALLOC_FL_KEEP_SIZE mode */
-	if (mode & ~FALLOC_FL_KEEP_SIZE)
-		return -EOPNOTSUPP;
-
-	offset = (offset >> sdp->sd_sb.sb_bsize_shift) <<
-		 sdp->sd_sb.sb_bsize_shift;
-
-	len = next - offset;
-	bytes = sdp->sd_max_rg_data * sdp->sd_sb.sb_bsize / 2;
-	if (!bytes)
-		bytes = UINT_MAX;
-
-	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
-	error = gfs2_glock_nq(&ip->i_gh);
-	if (unlikely(error))
-		goto out_uninit;
-
-	if (!gfs2_write_alloc_required(ip, offset, len))
-		goto out_unlock;
-
-	while (len > 0) {
-		if (len < bytes)
-			bytes = len;
-		al = gfs2_alloc_get(ip);
-		if (!al) {
-			error = -ENOMEM;
-			goto out_unlock;
-		}
-
-		error = gfs2_quota_lock_check(ip);
-		if (error)
-			goto out_alloc_put;
-
-retry:
-		gfs2_write_calc_reserv(ip, bytes, &data_blocks, &ind_blocks);
-
-		al->al_requested = data_blocks + ind_blocks;
-		error = gfs2_inplace_reserve(ip);
-		if (error) {
-			if (error == -ENOSPC && bytes > sdp->sd_sb.sb_bsize) {
-				bytes >>= 1;
-				goto retry;
-			}
-			goto out_qunlock;
-		}
-		max_bytes = bytes;
-		calc_max_reserv(ip, len, &max_bytes, &data_blocks, &ind_blocks);
-		al->al_requested = data_blocks + ind_blocks;
-
-		rblocks = RES_DINODE + ind_blocks + RES_STATFS + RES_QUOTA +
-			  RES_RG_HDR + gfs2_rg_blocks(al);
-		if (gfs2_is_jdata(ip))
-			rblocks += data_blocks ? data_blocks : 1;
-
-		error = gfs2_trans_begin(sdp, rblocks,
-					 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
-		if (error)
-			goto out_trans_fail;
-
-		error = fallocate_chunk(inode, offset, max_bytes, mode);
-		gfs2_trans_end(sdp);
-
-		if (error)
-			goto out_trans_fail;
-
-		len -= max_bytes;
-		offset += max_bytes;
-		gfs2_inplace_release(ip);
-		gfs2_quota_unlock(ip);
-		gfs2_alloc_put(ip);
-	}
-	goto out_unlock;
-
-out_trans_fail:
-	gfs2_inplace_release(ip);
-out_qunlock:
-	gfs2_quota_unlock(ip);
-out_alloc_put:
-	gfs2_alloc_put(ip);
-out_unlock:
-	gfs2_glock_dq(&ip->i_gh);
-out_uninit:
-	gfs2_holder_uninit(&ip->i_gh);
-	return error;
-}
-
-
 static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		       u64 start, u64 len)
 {
@@ -1562,7 +1305,6 @@ const struct inode_operations gfs2_file_iops = {
 	.getxattr = gfs2_getxattr,
 	.listxattr = gfs2_listxattr,
 	.removexattr = gfs2_removexattr,
-	.fallocate = gfs2_fallocate,
 	.fiemap = gfs2_fiemap,
 };