NTFS: $EA attributes can be both resident non-resident.

      Minor tidying.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

5 files changed, 35 insertions, 14 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 03015c7b236..bc6ec16ad1f 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -75,6 +75,7 @@ ToDo/Notes:
           for highly fragmented files, i.e. ones whose data attribute is split
           across multiple extents.   When such a case is encountered,
           EOPNOTSUPP is returned.
+        - $EA attributes can be both resident non-resident.
 
 2.1.24 - Lots of bug fixes and support more clean journal states.
 
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 8f23c60030c..1c0a4315876 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -1391,8 +1391,7 @@ retry_writepage:
                 if (NInoEncrypted(ni)) {
                         unlock_page(page);
                         BUG_ON(ni->type != AT_DATA);
-                        ntfs_debug("Denying write access to encrypted "
-                                        "file.");
+                        ntfs_debug("Denying write access to encrypted file.");
                         return -EACCES;
                 }
                 /* Compressed data streams are handled in compress.c. */
@@ -1508,8 +1507,8 @@ retry_writepage:
         /* Zero out of bounds area in the page cache page. */
         memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
         kunmap_atomic(kaddr, KM_USER0);
-        flush_dcache_mft_record_page(ctx->ntfs_ino);
         flush_dcache_page(page);
+        flush_dcache_mft_record_page(ctx->ntfs_ino);
         /* We are done with the page. */
         end_page_writeback(page);
         /* Finally, mark the mft record dirty, so it gets written back. */
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 338e47144fc..df2e2091f93 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -1411,7 +1411,7 @@ int ntfs_attr_can_be_non_resident(const ntfs_volume *vol, const ATTR_TYPE type)
  */
 int ntfs_attr_can_be_resident(const ntfs_volume *vol, const ATTR_TYPE type)
 {
-        if (type == AT_INDEX_ALLOCATION || type == AT_EA)
+        if (type == AT_INDEX_ALLOCATION)
                 return -EPERM;
         return 0;
 }
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index cf2a0e2330d..5fb341a16b5 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -1857,10 +1857,24 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
         if (ni->type != AT_INDEX_ALLOCATION) {
                 /* If file is encrypted, deny access, just like NT4. */
                 if (NInoEncrypted(ni)) {
+                        /*
+                         * Reminder for later: Encrypted files are _always_
+                         * non-resident so that the content can always be
+                         * encrypted.
+                         */
                         ntfs_debug("Denying write access to encrypted file.");
                         return -EACCES;
                 }
                 if (NInoCompressed(ni)) {
+                        /* Only unnamed $DATA attribute can be compressed. */
+                        BUG_ON(ni->type != AT_DATA);
+                        BUG_ON(ni->name_len);
+                        /*
+                         * Reminder for later: If resident, the data is not
+                         * actually compressed.  Only on the switch to non-
+                         * resident does compression kick in.  This is in
+                         * contrast to encrypted files (see above).
+                         */
                         ntfs_error(vi->i_sb, "Writing to compressed files is "
                                         "not implemented yet.  Sorry.");
                         return -EOPNOTSUPP;
diff --git a/fs/ntfs/layout.h b/fs/ntfs/layout.h
index 5c248d404f0..71b25dab819 100644
--- a/fs/ntfs/layout.h
+++ b/fs/ntfs/layout.h
@@ -1021,10 +1021,17 @@ enum {
         FILE_NAME_POSIX         = 0x00,
         /* This is the largest namespace. It is case sensitive and allows all
            Unicode characters except for: '\0' and '/'.  Beware that in
-           WinNT/2k files which eg have the same name except for their case
-           will not be distinguished by the standard utilities and thus a "del
-           filename" will delete both "filename" and "fileName" without
-           warning. */
+           WinNT/2k/2003 by default files which eg have the same name except
+           for their case will not be distinguished by the standard utilities
+           and thus a "del filename" will delete both "filename" and "fileName"
+           without warning.  However if for example Services For Unix (SFU) are
+           installed and the case sensitive option was enabled at installation
+           time, then you can create/access/delete such files.
+           Note that even SFU places restrictions on the filenames beyond the
+           '\0' and '/' and in particular the following set of characters is
+           not allowed: '"', '/', '<', '>', '\'.  All other characters,
+           including the ones no allowed in WIN32 namespace are allowed.
+           Tested with SFU 3.5 (this is now free) running on Windows XP. */
         FILE_NAME_WIN32         = 0x01,
         /* The standard WinNT/2k NTFS long filenames. Case insensitive.  All
            Unicode chars except: '\0', '"', '*', '/', ':', '<', '>', '?', '\',
@@ -2375,20 +2382,20 @@ typedef u8 EA_FLAGS;
 /*
  * Attribute: Extended attribute (EA) (0xe0).
  *
- * NOTE: Always non-resident. (Is this true?)
+ * NOTE: Can be resident or non-resident.
  *
  * Like the attribute list and the index buffer list, the EA attribute value is
  * a sequence of EA_ATTR variable length records.
- *
- * FIXME: It appears weird that the EA name is not unicode. Is it true?
  */
 typedef struct {
         le32 next_entry_offset; /* Offset to the next EA_ATTR. */
         EA_FLAGS flags;         /* Flags describing the EA. */
-        u8 ea_name_length;      /* Length of the name of the EA in bytes. */
+        u8 ea_name_length;      /* Length of the name of the EA in bytes
+                                   excluding the '\0' byte terminator. */
         le16 ea_value_length;   /* Byte size of the EA's value. */
-        u8 ea_name[0];          /* Name of the EA. */
-        u8 ea_value[0];         /* The value of the EA. Immediately follows
+        u8 ea_name[0];          /* Name of the EA.  Note this is ASCII, not
+                                   Unicode and it is zero terminated. */
+        u8 ea_value[0];         /* The value of the EA.  Immediately follows
                                    the name. */
 } __attribute__ ((__packed__)) EA_ATTR;