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update VFS documentation for method changes.

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2010-06-08 00:37:12 -04:00
parent b70a3e0702
commit 336fb3b97b
2 changed files with 39 additions and 10 deletions
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22
Documentation/filesystems/Locking
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@@ -92,8 +92,8 @@ prototypes:
void (*destroy_inode)(struct inode *);
void (*dirty_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*drop_inode) (struct inode *);
void (*delete_inode) (struct inode *);
int (*drop_inode) (struct inode *);
void (*evict_inode) (struct inode *);
void (*put_super) (struct super_block *);
void (*write_super) (struct super_block *);
int (*sync_fs)(struct super_block *sb, int wait);
@@ -101,14 +101,13 @@ prototypes:
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void (*clear_inode) (struct inode *);
void (*umount_begin) (struct super_block *);
int (*show_options)(struct seq_file *, struct vfsmount *);
ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
locking rules:
All may block.
All may block [not true, see below]
None have BKL
s_umount
alloc_inode:
@@ -116,22 +115,25 @@ destroy_inode:
dirty_inode: (must not sleep)
write_inode:
drop_inode: !!!inode_lock!!!
delete_inode:
evict_inode:
put_super: write
write_super: read
sync_fs: read
freeze_fs: read
unfreeze_fs: read
statfs: no
remount_fs: maybe (see below)
clear_inode:
statfs: maybe(read) (see below)
remount_fs: write
umount_begin: no
show_options: no (namespace_sem)
quota_read: no (see below)
quota_write: no (see below)
->remount_fs() will have the s_umount exclusive lock if it's already mounted.
When called from get_sb_single, it does NOT have the s_umount lock.
->statfs() has s_umount (shared) when called by ustat(2) (native or
compat), but that's an accident of bad API; s_umount is used to pin
the superblock down when we only have dev_t given us by userland to
identify the superblock. Everything else (statfs(), fstatfs(), etc.)
doesn't hold it when calling ->statfs() - superblock is pinned down
by resolving the pathname passed to syscall.
->quota_read() and ->quota_write() functions are both guaranteed to
be the only ones operating on the quota file by the quota code (via
dqio_sem) (unless an admin really wants to screw up something and