linux-ext4 - [PATCH] ext4: Cache the correct extent length for uninit extent.

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Message-Id: <1207044243-21455-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Date:	Tue,  1 Apr 2008 15:34:03 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	cmm@...ibm.com, tytso@....edu
Cc:	linux-ext4@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH] ext4: Cache the correct extent length for uninit extent.

When we convert uninitialized extent to initialized extent
we need to make sure we return the number of blocks in the
extent from the file system block corresponding to logical
file block. Other wise we cache wrong extent details and this
results in file system corruption.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
 fs/ext4/extents.c |   47 ++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 964d2c1..30f0f99 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2264,7 +2264,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 		ex->ee_len   = orig_ex.ee_len;
 		ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
 		ext4_ext_dirty(handle, inode, path + depth);
-		return le16_to_cpu(ex->ee_len);
+		/* zeroed the full extent */
+		return allocated;
 	}
 
 	/* ex1: ee_block to iblock - 1 : uninitialized */
@@ -2309,11 +2310,44 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 				ex->ee_len   = orig_ex.ee_len;
 				ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
 				ext4_ext_dirty(handle, inode, path + depth);
-				return le16_to_cpu(ex->ee_len);
+				/* zeroed the full extent */
+				return allocated;
 
 			} else if (err)
 				goto fix_extent_len;
 
+			/* We need to zero out the second half because
+			 * fallocate request can update file size and
+			 * converting the second half to initialized extent
+			 * implies that we can leak some junk data to user
+			 * space
+			 */
+			err =  ext4_ext_zeroout(inode, ex3);
+			if (err) {
+				/*
+				 * We should actually mark the
+				 * second half as uninit and return error
+				 * Insert would have changed the extent
+				 */
+				depth = ext_depth(inode);
+				ext4_ext_drop_refs(path);
+				path = ext4_ext_find_extent(inode,
+								iblock, path);
+				if (IS_ERR(path)) {
+					err = PTR_ERR(path);
+					return err;
+				}
+				ex = path[depth].p_ext;
+				err = ext4_ext_get_access(handle, inode,
+								path + depth);
+				if (err)
+					return err;
+				ext4_ext_mark_uninitialized(ex);
+				ext4_ext_dirty(handle, inode, path + depth);
+				return err;
+			}
+
+			/* zeroed the second half */
 			return allocated;
 		}
 		ex3 = &newex;
@@ -2331,7 +2365,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 			ex->ee_len   = orig_ex.ee_len;
 			ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
 			ext4_ext_dirty(handle, inode, path + depth);
-			return le16_to_cpu(ex->ee_len);
+			/* zeroed the full extent */
+			return allocated;
 
 		} else if (err)
 			goto fix_extent_len;
@@ -2379,7 +2414,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 			ex->ee_len   = orig_ex.ee_len;
 			ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
 			ext4_ext_dirty(handle, inode, path + depth);
-			return le16_to_cpu(ex->ee_len);
+			/* zero out the first half */
+			return allocated;
 		}
 	}
 	/*
@@ -2446,7 +2482,8 @@ insert:
 		ex->ee_len   = orig_ex.ee_len;
 		ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
 		ext4_ext_dirty(handle, inode, path + depth);
-		return le16_to_cpu(ex->ee_len);
+		/* zero out the first half */
+		return allocated;
 	} else if (err)
 		goto fix_extent_len;
 out:
-- 
1.5.5.rc1.22.g17689.dirty

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