The patch titled
Subject: mm/filemap.c: make global sync not clear error status of individual inodes
has been added to the -mm tree. Its filename is
fs-global-sync-to-not-clear-error-status-of-individual-inodes.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-global-sync-to-not-clear-error-status-of-individual-inodes.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-global-sync-to-not-clear-error-status-of-individual-inodes.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Junichi Nomura <j-nomura@xxxxxxxxxxxxx>
Subject: mm/filemap.c: make global sync not clear error status of individual inodes
filemap_fdatawait() is a function to wait for on-going writeback to
complete but also consume and clear error status of the mapping set during
writeback.
The latter functionality is critical for applications to detect writeback
error with system calls like fsync(2)/fdatasync(2).
However filemap_fdatawait() is also used by sync(2) or FIFREEZE ioctl,
which don't check error status of individual mappings.
As a result, fsync() may not be able to detect writeback error if events
happen in the following order:
Application System admin
----------------------------------------------------------
write data on page cache
Run sync command
writeback completes with error
filemap_fdatawait() clears error
fsync returns success
(but the data is not on disk)
This patch adds filemap_fdatawait_keep_errors() for call sites where
writeback error is not handled so that they don't clear error status.
Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Acked-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 7 +++-
fs/sync.c | 7 +++-
include/linux/fs.h | 1
mm/filemap.c | 67 ++++++++++++++++++++++++++++++++++---------
4 files changed, 67 insertions(+), 15 deletions(-)
diff -puN fs/fs-writeback.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes fs/fs-writeback.c
--- a/fs/fs-writeback.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes
+++ a/fs/fs-writeback.c
@@ -2121,7 +2121,12 @@ static void wait_sb_inodes(struct super_
iput(old_inode);
old_inode = inode;
- filemap_fdatawait(mapping);
+ /*
+ * We keep the error status of individual mapping so that
+ * applications can catch the writeback error using fsync(2).
+ * See filemap_fdatawait_keep_errors() for details.
+ */
+ filemap_fdatawait_keep_errors(mapping);
cond_resched();
diff -puN fs/sync.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes fs/sync.c
--- a/fs/sync.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes
+++ a/fs/sync.c
@@ -86,7 +86,12 @@ static void fdatawrite_one_bdev(struct b
static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
{
- filemap_fdatawait(bdev->bd_inode->i_mapping);
+ /*
+ * We keep the error status of individual mapping so that
+ * applications can catch the writeback error using fsync(2).
+ * See filemap_fdatawait_keep_errors() for details.
+ */
+ filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping);
}
/*
diff -puN include/linux/fs.h~fs-global-sync-to-not-clear-error-status-of-individual-inodes include/linux/fs.h
--- a/include/linux/fs.h~fs-global-sync-to-not-clear-error-status-of-individual-inodes
+++ a/include/linux/fs.h
@@ -2422,6 +2422,7 @@ extern int write_inode_now(struct inode
extern int filemap_fdatawrite(struct address_space *);
extern int filemap_flush(struct address_space *);
extern int filemap_fdatawait(struct address_space *);
+extern void filemap_fdatawait_keep_errors(struct address_space *);
extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
loff_t lend);
extern int filemap_write_and_wait(struct address_space *mapping);
diff -puN mm/filemap.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes mm/filemap.c
--- a/mm/filemap.c~fs-global-sync-to-not-clear-error-status-of-individual-inodes
+++ a/mm/filemap.c
@@ -331,23 +331,14 @@ int filemap_flush(struct address_space *
}
EXPORT_SYMBOL(filemap_flush);
-/**
- * filemap_fdatawait_range - wait for writeback to complete
- * @mapping: address space structure to wait for
- * @start_byte: offset in bytes where the range starts
- * @end_byte: offset in bytes where the range ends (inclusive)
- *
- * Walk the list of under-writeback pages of the given address space
- * in the given range and wait for all of them.
- */
-int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
- loff_t end_byte)
+static int __filemap_fdatawait_range(struct address_space *mapping,
+ loff_t start_byte, loff_t end_byte)
{
pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
struct pagevec pvec;
int nr_pages;
- int ret2, ret = 0;
+ int ret = 0;
if (end_byte < start_byte)
goto out;
@@ -374,6 +365,29 @@ int filemap_fdatawait_range(struct addre
cond_resched();
}
out:
+ return ret;
+}
+
+/**
+ * filemap_fdatawait_range - wait for writeback to complete
+ * @mapping: address space structure to wait for
+ * @start_byte: offset in bytes where the range starts
+ * @end_byte: offset in bytes where the range ends (inclusive)
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * in the given range and wait for all of them. Check error status of
+ * the address space and return it.
+ *
+ * Since the error status of the address space is cleared by this function,
+ * callers are responsible for checking the return value and handling and/or
+ * reporting the error.
+ */
+int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
+ loff_t end_byte)
+{
+ int ret, ret2;
+
+ ret = __filemap_fdatawait_range(mapping, start_byte, end_byte);
ret2 = filemap_check_errors(mapping);
if (!ret)
ret = ret2;
@@ -383,11 +397,38 @@ out:
EXPORT_SYMBOL(filemap_fdatawait_range);
/**
+ * filemap_fdatawait_keep_errors - wait for writeback without clearing errors
+ * @mapping: address space structure to wait for
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * and wait for all of them. Unlike filemap_fdatawait(), this function
+ * does not clear error status of the address space.
+ *
+ * Use this function if callers don't handle errors themselves. Expected
+ * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
+ * fsfreeze(8)
+ */
+void filemap_fdatawait_keep_errors(struct address_space *mapping)
+{
+ loff_t i_size = i_size_read(mapping->host);
+
+ if (i_size == 0)
+ return;
+
+ __filemap_fdatawait_range(mapping, 0, i_size - 1);
+}
+
+/**
* filemap_fdatawait - wait for all under-writeback pages to complete
* @mapping: address space structure to wait for
*
* Walk the list of under-writeback pages of the given address space
- * and wait for all of them.
+ * and wait for all of them. Check error status of the address space
+ * and return it.
+ *
+ * Since the error status of the address space is cleared by this function,
+ * callers are responsible for checking the return value and handling and/or
+ * reporting the error.
*/
int filemap_fdatawait(struct address_space *mapping)
{
_
Patches currently in -mm which might be from j-nomura@xxxxxxxxxxxxx are
fs-global-sync-to-not-clear-error-status-of-individual-inodes.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
