The commit is pushed to "branch-rh7-3.10.0-327.36.1.vz7.20.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.36.1.vz7.20.15
------>
commit b6b7fc7f1d2dbfef8fb8a8e109e33cb770ce43ac
Author: Maxim Patlasov <mpatla...@virtuozzo.com>
Date: Thu Dec 15 17:48:29 2016 +0400
fuse: trust server file size unless opened
Before the patch, the only way to pick up updated file size from server (in
a
scenario when local inode was created earlier, then the file was updated
from another node) was in fuse_open_common():
> atomic_inc(&fi->num_openers);
>
> if (atomic_read(&fi->num_openers) == 1) {
> err = fuse_getattr_size(inode, file, &size);
> ...
> spin_lock(&fc->lock);
> i_size_write(inode, size);
> spin_unlock(&fc->lock);
> }
This is correct, but someone may ask about i_size w/o open, e.g.: ls -l foo.
The patch ensures that every time the server reports us some file size, if
no
open-s happened yet (num_openers=0), fuse stores that server size in local
inode->i_size. This resolves the following problem:
# pstorage-mount -c test -l /var/log/f1.log /pcs1
# pstorage-mount -c test -l /var/log/f2.log /pcs2
# date > /pcs1/foo; ls -l /pcs1/foo /pcs2/foo
-rwx------ 1 root root 29 Dec 14 16:31 /pcs1/foo
-rwx------ 1 root root 29 Dec 14 16:31 /pcs2/foo
# date >> /pcs1/foo; ls -l /pcs1/foo /pcs2/foo
-rwx------ 1 root root 58 Dec 14 16:31 /pcs1/foo
-rwx------ 1 root root 29 Dec 14 16:31 /pcs2/foo
https://jira.sw.ru/browse/PSBM-57047
Signed-off-by: Maxim Patlasov <mpatla...@virtuozzo.com>
Acked-by: Dmitry Monakhov <dmonak...@openvz.org>
---
fs/fuse/file.c | 12 +++++++++++-
fs/fuse/fuse_i.h | 3 +++
fs/fuse/inode.c | 4 +++-
3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 501aa27..1bda994 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -296,12 +296,20 @@ int fuse_open_common(struct inode *inode, struct file
*file, bool isdir)
u64 size;
mutex_lock(&inode->i_mutex);
+
+ spin_lock(&fc->lock);
atomic_inc(&fi->num_openers);
if (atomic_read(&fi->num_openers) == 1) {
+ fi->i_size_unstable = 1;
+ spin_unlock(&fc->lock);
err = fuse_getattr_size(inode, file, &size);
if (err) {
+ spin_lock(&fc->lock);
atomic_dec(&fi->num_openers);
+ fi->i_size_unstable = 0;
+ spin_unlock(&fc->lock);
+
mutex_unlock(&inode->i_mutex);
fuse_release_common(file, FUSE_RELEASE);
return err;
@@ -309,8 +317,10 @@ int fuse_open_common(struct inode *inode, struct file
*file, bool isdir)
spin_lock(&fc->lock);
i_size_write(inode, size);
+ fi->i_size_unstable = 0;
+ spin_unlock(&fc->lock);
+ } else
spin_unlock(&fc->lock);
- }
mutex_unlock(&inode->i_mutex);
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 1d24bf6..22eb9c9 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -124,6 +124,9 @@ struct fuse_inode {
/** Mostly to detect very first open */
atomic_t num_openers;
+
+ /** Even though num_openers>0, trust server i_size */
+ int i_size_unstable;
};
/** FUSE inode state bits */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 5ccecae..f606deb 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -97,6 +97,7 @@ static struct inode *fuse_alloc_inode(struct super_block *sb)
fi->writectr = 0;
fi->orig_ino = 0;
fi->state = 0;
+ fi->i_size_unstable = 0;
INIT_LIST_HEAD(&fi->write_files);
INIT_LIST_HEAD(&fi->rw_files);
INIT_LIST_HEAD(&fi->queued_writes);
@@ -226,7 +227,8 @@ void fuse_change_attributes(struct inode *inode, struct
fuse_attr *attr,
* extend local i_size without keeping userspace server in sync. So,
* attr->size coming from server can be stale. We cannot trust it.
*/
- if (!is_wb || !S_ISREG(inode->i_mode))
+ if (!is_wb || !S_ISREG(inode->i_mode) ||
+ !atomic_read(&fi->num_openers) || fi->i_size_unstable)
i_size_write(inode, attr->size);
spin_unlock(&fc->lock);
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