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From: Carlos Maiolino <cmaiolino@redhat.com>
To: linux-fsdevel@vger.kernel.org
Cc: hch@lst.de, adilger@dilger.ca, sandeen@redhat.com, david@fromorbit.com
Subject: [PATCH 01/10] fs: Enable bmap() function to properly return errors
Date: Wed,  5 Dec 2018 10:17:19 +0100
Message-ID: <20181205091728.29903-2-cmaiolino@redhat.com> (raw)
In-Reply-To: <20181205091728.29903-1-cmaiolino@redhat.com>

By now, bmap() will either return the physical block number related to
the requested file offset or 0 in case of error or the requested offset
maps into a hole.
This patch makes the needed changes to enable bmap() to proper return
errors, using the return value as an error return, and now, a pointer
must be passed to bmap() to be filled with the mapped physical block.

It will change the behavior of bmap() on return:

- negative value in case of error
- zero on success or map fell into a hole

In case of a hole, the *block will be zero too

Since this is a prep patch, by now, the only error return is -EINVAL if
->bmap doesn't exist.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 drivers/md/md-bitmap.c | 16 ++++++++++------
 fs/inode.c             | 30 +++++++++++++++++-------------
 fs/jbd2/journal.c      | 22 +++++++++++++++-------
 include/linux/fs.h     |  2 +-
 mm/page_io.c           | 11 +++++++----
 5 files changed, 50 insertions(+), 31 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 1cd4f991792c..0668b2dd290e 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -363,7 +363,7 @@ static int read_page(struct file *file, unsigned long index,
 	int ret = 0;
 	struct inode *inode = file_inode(file);
 	struct buffer_head *bh;
-	sector_t block;
+	sector_t block, blk_cur;
 
 	pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
 		 (unsigned long long)index << PAGE_SHIFT);
@@ -374,17 +374,21 @@ static int read_page(struct file *file, unsigned long index,
 		goto out;
 	}
 	attach_page_buffers(page, bh);
-	block = index << (PAGE_SHIFT - inode->i_blkbits);
+	blk_cur = index << (PAGE_SHIFT - inode->i_blkbits);
 	while (bh) {
+		block = blk_cur;
+
 		if (count == 0)
 			bh->b_blocknr = 0;
 		else {
-			bh->b_blocknr = bmap(inode, block);
-			if (bh->b_blocknr == 0) {
-				/* Cannot use this file! */
+			ret = bmap(inode, &block);
+			if (ret || !block) {
 				ret = -EINVAL;
+				bh->b_blocknr = 0;
 				goto out;
 			}
+
+			bh->b_blocknr = block;
 			bh->b_bdev = inode->i_sb->s_bdev;
 			if (count < (1<<inode->i_blkbits))
 				count = 0;
@@ -398,7 +402,7 @@ static int read_page(struct file *file, unsigned long index,
 			set_buffer_mapped(bh);
 			submit_bh(REQ_OP_READ, 0, bh);
 		}
-		block++;
+		blk_cur++;
 		bh = bh->b_this_page;
 	}
 	page->index = index;
diff --git a/fs/inode.c b/fs/inode.c
index 0cd47fe0dbe5..db681d310465 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1580,21 +1580,25 @@ EXPORT_SYMBOL(iput);
 
 /**
  *	bmap	- find a block number in a file
- *	@inode: inode of file
- *	@block: block to find
- *
- *	Returns the block number on the device holding the inode that
- *	is the disk block number for the block of the file requested.
- *	That is, asked for block 4 of inode 1 the function will return the
- *	disk block relative to the disk start that holds that block of the
- *	file.
+ *	@inode:  inode owning the block number being requested
+ *	@*block: pointer containing the block to find
+ *
+ *	Replaces the value in *block with the block number on the device holding
+ *	corresponding to the requested block number in the file.
+ *	That is, asked for block 4 of inode 1 the function will replace the
+ *	4 in *block, with disk block relative to the disk start that holds that
+ *	block of the file.
+ *
+ *	Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
+ *	hole, returns 0 and *block is also set to 0.
  */
-sector_t bmap(struct inode *inode, sector_t block)
+int bmap(struct inode *inode, sector_t *block)
 {
-	sector_t res = 0;
-	if (inode->i_mapping->a_ops->bmap)
-		res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
-	return res;
+	if (!inode->i_mapping->a_ops->bmap)
+		return -EINVAL;
+
+	*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
+	return 0;
 }
 EXPORT_SYMBOL(bmap);
 
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 8ef6b6daaa7a..7acaf6f55404 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -814,18 +814,23 @@ int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
 {
 	int err = 0;
 	unsigned long long ret;
+	sector_t block = 0;
 
 	if (journal->j_inode) {
-		ret = bmap(journal->j_inode, blocknr);
-		if (ret)
-			*retp = ret;
-		else {
+		block = blocknr;
+		ret = bmap(journal->j_inode, &block);
+
+		if (ret || !block) {
 			printk(KERN_ALERT "%s: journal block not found "
 					"at offset %lu on %s\n",
 			       __func__, blocknr, journal->j_devname);
 			err = -EIO;
 			__journal_abort_soft(journal, err);
+
+		} else {
+			*retp = block;
 		}
+
 	} else {
 		*retp = blocknr; /* +journal->j_blk_offset */
 	}
@@ -1251,11 +1256,14 @@ journal_t *jbd2_journal_init_dev(struct block_device *bdev,
 journal_t *jbd2_journal_init_inode(struct inode *inode)
 {
 	journal_t *journal;
+	sector_t blocknr;
 	char *p;
-	unsigned long long blocknr;
+	int err = 0;
+
+	blocknr = 0;
+	err = bmap(inode, &blocknr);
 
-	blocknr = bmap(inode, 0);
-	if (!blocknr) {
+	if (err || !blocknr) {
 		pr_err("%s: Cannot locate journal superblock\n",
 			__func__);
 		return NULL;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5f7f67bd33a5..71dac6e00e27 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2811,7 +2811,7 @@ static inline ssize_t generic_write_sync(struct kiocb *iocb, ssize_t count)
 extern void emergency_sync(void);
 extern void emergency_remount(void);
 #ifdef CONFIG_BLOCK
-extern sector_t bmap(struct inode *, sector_t);
+extern int bmap(struct inode *, sector_t *);
 #endif
 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
 extern int inode_permission(struct inode *, int);
diff --git a/mm/page_io.c b/mm/page_io.c
index 57572ff46016..b52e3e2ec13c 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -177,8 +177,9 @@ int generic_swapfile_activate(struct swap_info_struct *sis,
 
 		cond_resched();
 
-		first_block = bmap(inode, probe_block);
-		if (first_block == 0)
+		first_block = probe_block;
+		ret = bmap(inode, &first_block);
+		if (ret || !first_block)
 			goto bad_bmap;
 
 		/*
@@ -193,9 +194,11 @@ int generic_swapfile_activate(struct swap_info_struct *sis,
 					block_in_page++) {
 			sector_t block;
 
-			block = bmap(inode, probe_block + block_in_page);
-			if (block == 0)
+			block = probe_block + block_in_page;
+			ret = bmap(inode, &block);
+			if (ret || !block)
 				goto bad_bmap;
+
 			if (block != first_block + block_in_page) {
 				/* Discontiguity */
 				probe_block++;
-- 
2.17.2

  reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-05  9:17 [PATCH 00/10 V2] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2018-12-05  9:17 ` Carlos Maiolino [this message]
2018-12-05  9:17 ` [PATCH 02/10] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
2018-12-05  9:17 ` [PATCH 03/10] ecryptfs: drop direct calls to ->bmap Carlos Maiolino
2018-12-05  9:17 ` [PATCH 04/10 V2] fibmap: Use bmap instead of ->bmap method in ioctl_fibmap Carlos Maiolino
2019-01-14 16:49   ` Christoph Hellwig
2019-02-04 11:34     ` Carlos Maiolino
2018-12-05  9:17 ` [PATCH 05/10] fs: Move start and length fiemap fields into fiemap_extent_info Carlos Maiolino
2019-01-14 16:50   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 06/10] iomap: Remove length and start fields from iomap_fiemap Carlos Maiolino
2019-01-14 16:51   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 07/10] fs: Use a void pointer to store fiemap_extent Carlos Maiolino
2019-01-14 16:53   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 08/10 V2] fiemap: Use a callback to fill fiemap extents Carlos Maiolino
2019-01-14 16:53   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 09/10 V2] Use FIEMAP for FIBMAP calls Carlos Maiolino
2018-12-05 17:36   ` Darrick J. Wong
2018-12-07  9:09     ` Carlos Maiolino
2018-12-07 20:14       ` Andreas Dilger
2019-02-04 15:11     ` Carlos Maiolino
2019-02-04 18:27       ` Darrick J. Wong
2019-02-06 13:37         ` Carlos Maiolino
2019-02-06 20:44           ` Darrick J. Wong
2019-02-06 21:13             ` Andreas Dilger
2019-02-07  9:52               ` Carlos Maiolino
2019-02-08  8:43                 ` Christoph Hellwig
2019-02-11 12:57                   ` Christoph Hellwig
2019-02-11 16:21                     ` Carlos Maiolino
2019-02-11 16:48                       ` Christoph Hellwig
2019-02-07 11:59             ` Carlos Maiolino
2019-02-07 17:02               ` Darrick J. Wong
2019-02-07 21:25                 ` Andreas Dilger
2019-02-08  8:46                   ` Christoph Hellwig
2019-02-08 10:36                     ` Carlos Maiolino
2019-02-08 21:03                       ` Andreas Dilger
2019-02-08  9:08                   ` Carlos Maiolino
2019-02-08  9:03                 ` Carlos Maiolino
2019-02-07 12:36             ` Carlos Maiolino
2019-02-07 18:16               ` Darrick J. Wong
2019-02-08  8:58                 ` Carlos Maiolino
2019-02-06 21:04           ` Andreas Dilger
2019-01-14 16:56   ` Christoph Hellwig
2019-02-05  9:56     ` Carlos Maiolino
2019-02-05 18:25       ` Christoph Hellwig
2019-02-06  9:50         ` Carlos Maiolino
2018-12-05  9:17 ` [PATCH 10/10] xfs: Get rid of ->bmap Carlos Maiolino
2018-12-05 17:37   ` Darrick J. Wong
2018-12-06 13:06     ` Carlos Maiolino
2018-12-06 18:56 ` [PATCH 00/10 V2] New ->fiemap infrastructure and ->bmap removal Andreas Grünbacher
2018-12-07  9:34   ` Carlos Maiolino
2019-01-14 16:50     ` Christoph Hellwig
2019-01-14 17:56       ` Andreas Grünbacher
2019-01-14 17:58         ` Christoph Hellwig

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