[PATCH v2 04/10] ntfs: preserve EA attribute lookup errors

[Baolin Liu <liubaolin12138@163.com>]

From: Baolin Liu <liubaolin@kylinos.cn>

ntfs_attr_exist() treats lookup failures as absence. Using it while
updating EAs can select creation or removal paths after an allocation
or I/O failure.

Use an EA-local lookup helper that preserves errors from mapping the
MFT record, allocating the search context and looking up the attribute.
Check both EA attributes before modifying either and return EUCLEAN if
only one exists. Keep the known presence state for the final update.

Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
---
 fs/ntfs/ea.c | 51 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/fs/ntfs/ea.c b/fs/ntfs/ea.c
index 5c6facae4ed5..f5a112495fc9 100644
--- a/fs/ntfs/ea.c
+++ b/fs/ntfs/ea.c
@@ -181,6 +181,29 @@ static inline int ea_packed_size(const struct ea_attr *p_ea)
 	return 5 + p_ea->ea_name_length + le16_to_cpu(p_ea->ea_value_length);
 }
 
+/* Unlike ntfs_attr_exist(), preserve lookup errors. */
+static int ntfs_ea_attr_lookup(struct ntfs_inode *ni, __le32 type)
+{
+	struct ntfs_attr_search_ctx *ctx;
+	struct mft_record *mrec;
+	int err;
+
+	mrec = map_mft_record(ni);
+	if (IS_ERR(mrec))
+		return PTR_ERR(mrec);
+	ctx = ntfs_attr_get_search_ctx(ni, mrec);
+	if (!ctx) {
+		err = -ENOMEM;
+		goto out;
+	}
+	err = ntfs_attr_lookup(type, AT_UNNAMED, 0, CASE_SENSITIVE,
+			       0, NULL, 0, ctx);
+	ntfs_attr_put_search_ctx(ctx);
+out:
+	unmap_mft_record(ni);
+	return err;
+}
+
 /*
  * Set a new EA, and set EA_INFORMATION accordingly
  *
@@ -198,7 +221,8 @@ static int ntfs_set_ea(struct inode *inode, const char *name, size_t name_len,
 {
 	struct ntfs_inode *ni = NTFS_I(inode);
 	struct ea_information *p_ea_info = NULL;
-	int ea_packed, err = 0;
+	int ea_packed, err = 0, ea_err;
+	bool has_ea;
 	struct ea_attr *p_ea;
 	u32 ea_info_qsize = 0;
 	char *ea_buf = NULL;
@@ -211,7 +235,16 @@ static int ntfs_set_ea(struct inode *inode, const char *name, size_t name_len,
 	if (name_len > 255)
 		return -ENAMETOOLONG;
 
-	if (ntfs_attr_exist(ni, AT_EA_INFORMATION, AT_UNNAMED, 0)) {
+	err = ntfs_ea_attr_lookup(ni, AT_EA_INFORMATION);
+	if (err && err != -ENOENT)
+		return err;
+	ea_err = ntfs_ea_attr_lookup(ni, AT_EA);
+	if (ea_err && ea_err != -ENOENT)
+		return ea_err;
+	if (!err != !ea_err)
+		return -EUCLEAN;
+	has_ea = !err;
+	if (has_ea) {
 		p_ea_info = ntfs_attr_readall(ni, AT_EA_INFORMATION, NULL, 0,
 						&ea_info_size);
 		if (IS_ERR(p_ea_info)) {
@@ -230,15 +263,9 @@ static int ntfs_set_ea(struct inode *inode, const char *name, size_t name_len,
 			ea_buf = NULL;
 			goto out;
 		}
-		if (!ea_buf) {
-			ea_info_qsize = 0;
-			kvfree(p_ea_info);
-			goto create_ea_info;
-		}
 
 		ea_info_qsize = le32_to_cpu(p_ea_info->ea_query_length);
 	} else {
-create_ea_info:
 		p_ea_info = kzalloc_obj(struct ea_information, GFP_NOFS);
 		if (!p_ea_info)
 			return -ENOMEM;
@@ -249,12 +276,6 @@ static int ntfs_set_ea(struct inode *inode, const char *name, size_t name_len,
 		if (err)
 			goto out;
 
-		if (ntfs_attr_exist(ni, AT_EA, AT_UNNAMED, 0)) {
-			err = ntfs_attr_remove(ni, AT_EA, AT_UNNAMED, 0);
-			if (err)
-				goto out;
-		}
-
 		goto alloc_new_ea;
 	}
 
@@ -404,7 +425,7 @@ static int ntfs_set_ea(struct inode *inode, const char *name, size_t name_len,
 	/*
 	 * no EA or EA_INFORMATION : add them
 	 */
-	if (!ntfs_attr_exist(ni, AT_EA, AT_UNNAMED, 0)) {
+	if (!has_ea) {
 		err = ntfs_attr_add(ni, AT_EA, AT_UNNAMED, 0, ea_buf,
 				ea_info_qsize + new_ea_size);
 		if (err)
-- 
2.51.0