From: Jan Kara <jack@xxxxxxx>
Subject: fs: return EAGAIN when O_NONBLOCK write should block on frozen fs
When user asks for O_NONBLOCK behavior for a file descriptor, return
EAGAIN instead of blocking on a frozen filesystem.
This is needed so we can fix a hang with BSD accounting on frozen
filesystems.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Acked-by: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxx>
Cc: Nikola Ciprich <nikola.ciprich@xxxxxxxxxxx>
Cc: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/file.c | 3 ++-
fs/cifs/file.c | 3 ++-
fs/fuse/file.c | 3 ++-
fs/ntfs/file.c | 3 ++-
fs/ocfs2/file.c | 3 ++-
fs/splice.c | 3 ++-
fs/xfs/xfs_file.c | 3 ++-
include/linux/fs.h | 10 ++++++++++
mm/filemap.c | 3 ++-
9 files changed, 26 insertions(+), 8 deletions(-)
diff -puN fs/btrfs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/btrfs/file.c
--- a/fs/btrfs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/btrfs/file.c
@@ -1509,7 +1509,8 @@ static ssize_t btrfs_file_aio_write(stru
size_t count, ocount;
bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
mutex_lock(&inode->i_mutex);
diff -puN fs/cifs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/cifs/file.c
--- a/fs/cifs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/cifs/file.c
@@ -2510,7 +2510,8 @@ cifs_writev(struct kiocb *iocb, const st
BUG_ON(iocb->ki_pos != pos);
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
/*
* We need to hold the sem to be sure nobody modifies lock list
diff -puN fs/fuse/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/fuse/file.c
--- a/fs/fuse/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/fuse/file.c
@@ -971,7 +971,8 @@ static ssize_t fuse_file_aio_write(struc
return err;
count = ocount;
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
mutex_lock(&inode->i_mutex);
/* We can write back this queue in page reclaim */
diff -puN fs/ntfs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/ntfs/file.c
--- a/fs/ntfs/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/ntfs/file.c
@@ -2129,7 +2129,8 @@ static ssize_t ntfs_file_aio_write(struc
BUG_ON(iocb->ki_pos != pos);
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
mutex_lock(&inode->i_mutex);
ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
mutex_unlock(&inode->i_mutex);
diff -puN fs/ocfs2/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/ocfs2/file.c
--- a/fs/ocfs2/file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/ocfs2/file.c
@@ -2247,7 +2247,8 @@ static ssize_t ocfs2_file_aio_write(stru
if (iocb->ki_left == 0)
return 0;
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
appending = file->f_flags & O_APPEND ? 1 : 0;
direct_io = file->f_flags & O_DIRECT ? 1 : 0;
diff -puN fs/splice.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/splice.c
--- a/fs/splice.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/splice.c
@@ -998,7 +998,8 @@ generic_file_splice_write(struct pipe_in
};
ssize_t ret;
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(out))
+ return -EAGAIN;
pipe_lock(pipe);
diff -puN fs/xfs/xfs_file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs fs/xfs/xfs_file.c
--- a/fs/xfs/xfs_file.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/fs/xfs/xfs_file.c
@@ -775,7 +775,8 @@ xfs_file_aio_write(
if (ocount == 0)
return 0;
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
ret = -EIO;
diff -puN include/linux/fs.h~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs include/linux/fs.h
--- a/include/linux/fs.h~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/include/linux/fs.h
@@ -1400,6 +1400,16 @@ static inline int sb_start_write_trylock
return __sb_start_write(sb, SB_FREEZE_WRITE, false);
}
+/*
+ * sb_start_write() for writing into a file. When file has O_NONBLOCK set,
+ * we use trylock semantics, otherwise we block on frozen filesystem.
+ */
+static inline int sb_start_file_write(struct file *file)
+{
+ return __sb_start_write(file->f_mapping->host->i_sb, SB_FREEZE_WRITE,
+ !(file->f_flags & O_NONBLOCK));
+}
+
/**
* sb_start_pagefault - get write access to a superblock from a page fault
* @sb: the super we write to
diff -puN mm/filemap.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs mm/filemap.c
--- a/mm/filemap.c~fs-return-eagain-when-o_nonblock-write-should-block-on-frozen-fs
+++ a/mm/filemap.c
@@ -2527,7 +2527,8 @@ ssize_t generic_file_aio_write(struct ki
BUG_ON(iocb->ki_pos != pos);
- sb_start_write(inode->i_sb);
+ if (!sb_start_file_write(file))
+ return -EAGAIN;
mutex_lock(&inode->i_mutex);
ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
mutex_unlock(&inode->i_mutex);
_
--
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