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Btrfs: send, lower mem requirements for processing xattrs 

Maximum xattr size can be up to nearly the leaf size. For an fs with a
leaf size larger than the page size, using kmalloc requires allocating
multiple pages that are contiguous, which might not be possible if
there's heavy memory fragmentation. Therefore fallback to vmalloc if
we fail to allocate with kmalloc. Also start with a smaller buffer size,
since xattr values typically are smaller than a page.

Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-08-20 10:45:45 +01:00 committed by Chris Mason
parent f87c4318af
commit 4395e0c4da
1 changed files with 32 additions and 8 deletions
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40
fs/btrfs/send.c
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@ -986,11 +986,13 @@ static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
int num;
u8 type;
if (found_key->type == BTRFS_XATTR_ITEM_KEY)
buf_len = BTRFS_MAX_XATTR_SIZE(root);
else
buf_len = PATH_MAX;
/*
* Start with a small buffer (1 page). If later we end up needing more
* space, which can happen for xattrs on a fs with a leaf size greater
* then the page size, attempt to increase the buffer. Typically xattr
* values are small.
*/
buf_len = PATH_MAX;
buf = kmalloc(buf_len, GFP_NOFS);
if (!buf) {
ret = -ENOMEM;
@ -1017,7 +1019,7 @@ static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
ret = -ENAMETOOLONG;
goto out;
}
if (name_len + data_len > buf_len) {
if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root)) {
ret = -E2BIG;
goto out;
}
@ -1025,12 +1027,34 @@ static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
/*
* Path too long
*/
if (name_len + data_len > buf_len) {
if (name_len + data_len > PATH_MAX) {
ret = -ENAMETOOLONG;
goto out;
}
}
if (name_len + data_len > buf_len) {
buf_len = name_len + data_len;
if (is_vmalloc_addr(buf)) {
vfree(buf);
buf = NULL;
} else {
char *tmp = krealloc(buf, buf_len,
GFP_NOFS | __GFP_NOWARN);
if (!tmp)
kfree(buf);
buf = tmp;
}
if (!buf) {
buf = vmalloc(buf_len);
if (!buf) {
ret = -ENOMEM;
goto out;
}
}
}
read_extent_buffer(eb, buf, (unsigned long)(di + 1),
name_len + data_len);
@ -1051,7 +1075,7 @@ static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
}
out:
kfree(buf);
kvfree(buf);
return ret;
}