From 74d392aaabfc890cc1f0e80fc5ff13e5d3bcf4c9 Mon Sep 17 00:00:00 2001 From: Vadim Lobanov Date: Fri, 29 Sep 2006 02:01:43 -0700 Subject: [PATCH] Clean up expand_fdtable() and expand_files() Perform a code cleanup against the expand_fdtable() and expand_files() functions inside fs/file.c. It aims to make the flow of code within these functions simpler and easier to understand, via added comments and modest refactoring. Signed-off-by: Vadim Lobanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/file.c | 76 +++++++++++++++++++++++++++++---------------------------------- 1 file changed, 35 insertions(+), 41 deletions(-) (limited to 'fs/file.c') diff --git a/fs/file.c b/fs/file.c index 8d3bfca7714..2a991ac8e56 100644 --- a/fs/file.c +++ b/fs/file.c @@ -288,71 +288,65 @@ out: } /* - * Expands the file descriptor table - it will allocate a new fdtable and - * both fd array and fdset. It is expected to be called with the - * files_lock held. + * Expand the file descriptor table. + * This function will allocate a new fdtable and both fd array and fdset, of + * the given size. + * Return <0 error code on error; 1 on successful completion. + * The files->file_lock should be held on entry, and will be held on exit. */ static int expand_fdtable(struct files_struct *files, int nr) __releases(files->file_lock) __acquires(files->file_lock) { - int error = 0; - struct fdtable *fdt; - struct fdtable *nfdt = NULL; + struct fdtable *new_fdt, *cur_fdt; spin_unlock(&files->file_lock); - nfdt = alloc_fdtable(nr); - if (!nfdt) { - error = -ENOMEM; - spin_lock(&files->file_lock); - goto out; - } - + new_fdt = alloc_fdtable(nr); spin_lock(&files->file_lock); - fdt = files_fdtable(files); + if (!new_fdt) + return -ENOMEM; /* - * Check again since another task may have expanded the - * fd table while we dropped the lock + * Check again since another task may have expanded the fd table while + * we dropped the lock */ - if (nr >= fdt->max_fds || nr >= fdt->max_fdset) { - copy_fdtable(nfdt, fdt); + cur_fdt = files_fdtable(files); + if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) { + /* Continue as planned */ + copy_fdtable(new_fdt, cur_fdt); + rcu_assign_pointer(files->fdt, new_fdt); + free_fdtable(cur_fdt); } else { - /* Somebody expanded while we dropped file_lock */ + /* Somebody else expanded, so undo our attempt */ spin_unlock(&files->file_lock); - __free_fdtable(nfdt); + __free_fdtable(new_fdt); spin_lock(&files->file_lock); - goto out; } - rcu_assign_pointer(files->fdt, nfdt); - free_fdtable(fdt); -out: - return error; + return 1; } /* * Expand files. - * Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked. - * Should be called with the files->file_lock spinlock held for write. + * This function will expand the file structures, if the requested size exceeds + * the current capacity and there is room for expansion. + * Return <0 error code on error; 0 when nothing done; 1 when files were + * expanded and execution may have blocked. + * The files->file_lock should be held on entry, and will be held on exit. */ int expand_files(struct files_struct *files, int nr) { - int err, expand = 0; struct fdtable *fdt; fdt = files_fdtable(files); - if (nr >= fdt->max_fdset || nr >= fdt->max_fds) { - if (fdt->max_fdset >= NR_OPEN || - fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) { - err = -EMFILE; - goto out; - } - expand = 1; - if ((err = expand_fdtable(files, nr))) - goto out; - } - err = expand; -out: - return err; + /* Do we need to expand? */ + if (nr < fdt->max_fdset && nr < fdt->max_fds) + return 0; + /* Can we expand? */ + if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN || + nr >= NR_OPEN) + return -EMFILE; + + /* All good, so we try */ + return expand_fdtable(files, nr); } static void __devinit fdtable_defer_list_init(int cpu) -- cgit v1.2.3 From 327dcaadc0bc08ad081aa8e36b6ec7ad7aa45e30 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 29 Sep 2006 02:01:44 -0700 Subject: [PATCH] expand_fdtable(): remove pointless unlock+lock This unlock/lock on a super-unlikely path isn't worth the kernel text. Cc: Vadim Lobanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/file.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'fs/file.c') diff --git a/fs/file.c b/fs/file.c index 2a991ac8e56..8e81775c5dc 100644 --- a/fs/file.c +++ b/fs/file.c @@ -317,9 +317,7 @@ static int expand_fdtable(struct files_struct *files, int nr) free_fdtable(cur_fdt); } else { /* Somebody else expanded, so undo our attempt */ - spin_unlock(&files->file_lock); __free_fdtable(new_fdt); - spin_lock(&files->file_lock); } return 1; } -- cgit v1.2.3