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Date: Tue, 16 Aug 2011 15:14:39 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH] ext4: improve handling of conflincting mount options
If the user explicitly specifies conflicting mount options for
delalloc or dioread_nolock and data=journal, fail the mount, instead
of printing a warning and continuing (since many user's won't look at
dmesg and notice the warning).
Also, print a single warning that data=journal implies that delayed
allocation is not on by default (since it's not supported), and
furthermore that O_DIRECT is not supported. Improve the text in
Documentation/filesystems/ext4.txt so this is clear there as well.
Similarly, if the dioread_nolock mount option is specified when the
file system block size != PAGE_SIZE, fail the mount instead of
printing a warning message and ignoring the mount option.
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
n.b. I plan to follow this up with a patch to the mount man page in
util-linux-ng
Documentation/filesystems/ext4.txt | 8 ++++--
fs/ext4/ext4.h | 3 ++
fs/ext4/super.c | 46 +++++++++++++++++++++---------------
3 files changed, 35 insertions(+), 22 deletions(-)
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 232a575..168242b 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -160,7 +160,9 @@ noload if the filesystem was not unmounted cleanly,
lead to any number of problems.
data=journal All data are committed into the journal prior to being
- written into the main file system.
+ written into the main file system. Enabling
+ this mode will disable delayed allocation and
+ O_DIRECT support.
data=ordered (*) All data are forced directly out to the main file
system prior to its metadata being committed to the
@@ -419,8 +421,8 @@ written to the journal first, and then to its final location.
In the event of a crash, the journal can be replayed, bringing both data and
metadata into a consistent state. This mode is the slowest except when data
needs to be read from and written to disk at the same time where it
-outperforms all others modes. Currently ext4 does not have delayed
-allocation support if this data journalling mode is selected.
+outperforms all others modes. Enabling this mode will disable delayed
+allocation and O_DIRECT support.
/proc entries
=============
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e717dfd..062c668 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -917,6 +917,9 @@ struct ext4_inode_info {
#define EXT4_MOUNT_DISCARD 0x40000000 /* Issue DISCARD requests */
#define EXT4_MOUNT_INIT_INODE_TABLE 0x80000000 /* Initialize uninitialized itables */
+#define EXT4_MOUNT2_EXPLICIT_DELALLOC 0x00000001 /* User explicitly
+ specified delalloc */
+
#define clear_opt(sb, opt) EXT4_SB(sb)->s_mount_opt &= \
~EXT4_MOUNT_##opt
#define set_opt(sb, opt) EXT4_SB(sb)->s_mount_opt |= \
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 44d0c8d..c3e3a80 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1801,6 +1801,7 @@ set_qf_format:
break;
case Opt_nodelalloc:
clear_opt(sb, DELALLOC);
+ clear_opt2(sb, EXPLICIT_DELALLOC);
break;
case Opt_mblk_io_submit:
set_opt(sb, MBLK_IO_SUBMIT);
@@ -1817,6 +1818,7 @@ set_qf_format:
break;
case Opt_delalloc:
set_opt(sb, DELALLOC);
+ set_opt2(sb, EXPLICIT_DELALLOC);
break;
case Opt_block_validity:
set_opt(sb, BLOCK_VALIDITY);
@@ -3224,6 +3226,31 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
&journal_ioprio, NULL, 0))
goto failed_mount;
+ if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
+ printk_once(KERN_WARNING "EXT4-fs: Warning: mounting "
+ "with data=journal disables delayed "
+ "allocation and O_DIRECT support!\n");
+ if (test_opt2(sb, EXPLICIT_DELALLOC)) {
+ ext4_msg(sb, KERN_ERR, "can't mount with "
+ "both data=journal and delalloc");
+ goto failed_mount;
+ }
+ if (test_opt(sb, DIOREAD_NOLOCK)) {
+ ext4_msg(sb, KERN_ERR, "can't mount with "
+ "both data=journal and delalloc");
+ goto failed_mount;
+ }
+ if (test_opt(sb, DELALLOC))
+ clear_opt(sb, DELALLOC);
+ }
+ if (test_opt(sb, DIOREAD_NOLOCK)) {
+ if (sb->s_blocksize < PAGE_SIZE) {
+ ext4_msg(sb, KERN_ERR, "can't mount with "
+ "dioread_nolock if block size != PAGE_SIZE");
+ goto failed_mount;
+ }
+ }
+
sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
(test_opt(sb, POSIX_ACL) ? MS_POSIXACL : 0);
@@ -3679,25 +3706,6 @@ no_journal:
"available");
}
- if (test_opt(sb, DELALLOC) &&
- (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)) {
- ext4_msg(sb, KERN_WARNING, "Ignoring delalloc option - "
- "requested data journaling mode");
- clear_opt(sb, DELALLOC);
- }
- if (test_opt(sb, DIOREAD_NOLOCK)) {
- if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
- ext4_msg(sb, KERN_WARNING, "Ignoring dioread_nolock "
- "option - requested data journaling mode");
- clear_opt(sb, DIOREAD_NOLOCK);
- }
- if (sb->s_blocksize < PAGE_SIZE) {
- ext4_msg(sb, KERN_WARNING, "Ignoring dioread_nolock "
- "option - block size is too small");
- clear_opt(sb, DIOREAD_NOLOCK);
- }
- }
-
err = ext4_setup_system_zone(sb);
if (err) {
ext4_msg(sb, KERN_ERR, "failed to initialize system "
--
1.7.4.1.22.gec8e1.dirty
--
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