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[PATCH v2 01/11] switch befs long symlinks to page_symlink_operations

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From: Al Viro <viro@zeniv.linux.org.uk>

just give them the right ->readpage()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/befs/linuxvfs.c | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
index 46aedac..1c8b0dc 100644
--- a/fs/befs/linuxvfs.c
+++ b/fs/befs/linuxvfs.c
@@ -42,7 +42,7 @@ static struct inode *befs_iget(struct super_block *, unsigned long);
 static struct inode *befs_alloc_inode(struct super_block *sb);
 static void befs_destroy_inode(struct inode *inode);
 static void befs_destroy_inodecache(void);
-static const char *befs_follow_link(struct dentry *, void **);
+static int befs_symlink_readpage(struct file *, struct page *);
 static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
 			char **out, int *out_len);
 static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
@@ -79,10 +79,8 @@ static const struct address_space_operations befs_aops = {
 	.bmap		= befs_bmap,
 };
 
-static const struct inode_operations befs_symlink_inode_operations = {
-	.readlink	= generic_readlink,
-	.follow_link	= befs_follow_link,
-	.put_link	= kfree_put_link,
+static const struct address_space_operations befs_symlink_aops = {
+	.readpage	= befs_symlink_readpage,
 };
 
 /* 
@@ -398,7 +396,8 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino)
 		inode->i_fop = &befs_dir_operations;
 	} else if (S_ISLNK(inode->i_mode)) {
 		if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
-			inode->i_op = &befs_symlink_inode_operations;
+			inode->i_op = &page_symlink_inode_operations;
+			inode->i_mapping->a_ops = &befs_symlink_aops;
 		} else {
 			inode->i_link = befs_ino->i_data.symlink;
 			inode->i_op = &simple_symlink_inode_operations;
@@ -463,31 +462,35 @@ befs_destroy_inodecache(void)
  * The data stream become link name. Unless the LONG_SYMLINK
  * flag is set.
  */
-static const char *
-befs_follow_link(struct dentry *dentry, void **cookie)
+static int befs_symlink_readpage(struct file *unused, struct page *page)
 {
-	struct super_block *sb = dentry->d_sb;
-	struct befs_inode_info *befs_ino = BEFS_I(d_inode(dentry));
+	struct inode *inode = page->mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct befs_inode_info *befs_ino = BEFS_I(inode);
 	befs_data_stream *data = &befs_ino->i_data.ds;
 	befs_off_t len = data->size;
-	char *link;
+	char *link = kmap(page);
 
-	if (len == 0) {
+	if (len == 0 || len > PAGE_SIZE) {
 		befs_error(sb, "Long symlink with illegal length");
-		return ERR_PTR(-EIO);
+		goto fail;
 	}
 	befs_debug(sb, "Follow long symlink");
 
-	link = kmalloc(len, GFP_NOFS);
-	if (!link)
-		return ERR_PTR(-ENOMEM);
 	if (befs_read_lsymlink(sb, data, link, len) != len) {
-		kfree(link);
 		befs_error(sb, "Failed to read entire long symlink");
-		return ERR_PTR(-EIO);
+		goto fail;
 	}
 	link[len - 1] = '\0';
-	return *cookie = link;
+	SetPageUptodate(page);
+	kunmap(page);
+	unlock_page(page);
+	return 0;
+fail:
+	SetPageError(page);
+	kunmap(page);
+	unlock_page(page);
+	return -EIO;
 }
 
 /*
-- 
2.1.4

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Thread

[PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 02/11] logfs: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 08/11] teach page_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 10/11] teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 11/11] teach nfs_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 06/11] don't put symlink bodies in pagecache into highmem Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 01/11] switch befs long symlinks to page_symlink_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 03/11] udf: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 09/11] teach shmem_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 04/11] ufs: get rid of ->setattr() for symlinks Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-09 18:30 +0100
    Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 19:30 +0100
      Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 01:20 +0100
        Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 03:50 +0100
          Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-12-11 08:50 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode NeilBrown <neilb@suse.com> - 2015-12-09 23:00 +0100

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